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* Cancel initialize and TRIM before vdev_metaslab_fini()Brian Behlendorf2019-12-261-6/+7
| | | | | | | | | | | Any running 'zpool initialize' or TRIM must be cancelled prior to the vdev_metaslab_fini() call in spa_vdev_remove_log() which will unload the metaslabs and set ms->ms_group == NULL. Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: Kjeld Schouten <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #8602 Closes #9751
* Fix use-after-free of vd_path in spa_vdev_remove()Matthew Ahrens2019-12-111-11/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After spa_vdev_remove_aux() is called, the config nvlist is no longer valid, as it's been replaced by the new one (with the specified device removed). Therefore any pointers into the nvlist are no longer valid. So we can't save the result of `fnvlist_lookup_string(nv, ZPOOL_CONFIG_PATH)` (in vd_path) across the call to spa_vdev_remove_aux(). Instead, use spa_strdup() to save a copy of the string before calling spa_vdev_remove_aux. Found by AddressSanitizer: ERROR: AddressSanitizer: heap-use-after-free on address ... READ of size 34 at 0x608000a1fcd0 thread T686 #0 0x7fe88b0c166d (/usr/lib/x86_64-linux-gnu/libasan.so.4+0x5166d) #1 0x7fe88a5acd6e in spa_strdup spa_misc.c:1447 #2 0x7fe88a688034 in spa_vdev_remove vdev_removal.c:2259 #3 0x55ffbc7748f8 in ztest_vdev_aux_add_remove ztest.c:3229 #4 0x55ffbc769fba in ztest_execute ztest.c:6714 #5 0x55ffbc779a90 in ztest_thread ztest.c:6761 #6 0x7fe889cbc6da in start_thread #7 0x7fe8899e588e in __clone 0x608000a1fcd0 is located 48 bytes inside of 88-byte region freed by thread T686 here: #0 0x7fe88b14e7b8 in __interceptor_free #1 0x7fe88ae541c5 in nvlist_free nvpair.c:874 #2 0x7fe88ae543ba in nvpair_free nvpair.c:844 #3 0x7fe88ae57400 in nvlist_remove_nvpair nvpair.c:978 #4 0x7fe88a683c81 in spa_vdev_remove_aux vdev_removal.c:185 #5 0x7fe88a68857c in spa_vdev_remove vdev_removal.c:2221 #6 0x55ffbc7748f8 in ztest_vdev_aux_add_remove ztest.c:3229 #7 0x55ffbc769fba in ztest_execute ztest.c:6714 #8 0x55ffbc779a90 in ztest_thread ztest.c:6761 #9 0x7fe889cbc6da in start_thread Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> Closes #9706
* Replace ASSERTV macro with compiler annotationMatthew Macy2019-12-051-3/+3
| | | | | | | | | | | Remove the ASSERTV macro and handle suppressing unused compiler warnings for variables only in ASSERTs using the __attribute__((unused)) compiler annotation. The annotation is understood by both gcc and clang. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Jorgen Lundman <[email protected]> Signed-off-by: Matt Macy <[email protected]> Closes #9671
* Enable use of DTRACE_PROBE* macros in "spl" modulePrakash Surya2019-11-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | This change modifies some of the infrastructure for enabling the use of the DTRACE_PROBE* macros, such that we can use tehm in the "spl" module. Currently, when the DTRACE_PROBE* macros are used, they get expanded to create new functions, and these dynamically generated functions become part of the "zfs" module. Since the "spl" module does not depend on the "zfs" module, the use of DTRACE_PROBE* in the "spl" module would result in undefined symbols being used in the "spl" module. Specifically, DTRACE_PROBE* would turn into a function call, and the function being called would be a symbol only contained in the "zfs" module; which results in a linker and/or runtime error. Thus, this change adds the necessary logic to the "spl" module, to mirror the tracing functionality available to the "zfs" module. After this change, we'll have a "trace_zfs.h" header file which defines the probes available only to the "zfs" module, and a "trace_spl.h" header file which defines the probes available only to the "spl" module. Reviewed by: Brad Lewis <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Prakash Surya <[email protected]> Closes #9525
* Reduce loaded range tree memory usagePaul Dagnelie2019-10-091-32/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements a new tree structure for ZFS, and uses it to store range trees more efficiently. The new structure is approximately a B-tree, though there are some small differences from the usual characterizations. The tree has core nodes and leaf nodes; each contain data elements, which the elements in the core nodes acting as separators between its children. The difference between core and leaf nodes is that the core nodes have an array of children, while leaf nodes don't. Every node in the tree may be only partially full; in most cases, they are all at least 50% full (in terms of element count) except for the root node, which can be less full. Underfull nodes will steal from their neighbors or merge to remain full enough, while overfull nodes will split in two. The data elements are contained in tree-controlled buffers; they are copied into these on insertion, and overwritten on deletion. This means that the elements are not independently allocated, which reduces overhead, but also means they can't be shared between trees (and also that pointers to them are only valid until a side-effectful tree operation occurs). The overhead varies based on how dense the tree is, but is usually on the order of about 50% of the element size; the per-node overheads are very small, and so don't make a significant difference. The trees can accept arbitrary records; they accept a size and a comparator to allow them to be used for a variety of purposes. The new trees replace the AVL trees used in the range trees today. Currently, the range_seg_t structure contains three 8 byte integers of payload and two 24 byte avl_tree_node_ts to handle its storage in both an offset-sorted tree and a size-sorted tree (total size: 64 bytes). In the new model, the range seg structures are usually two 4 byte integers, but a separate one needs to exist for the size-sorted and offset-sorted tree. Between the raw size, the 50% overhead, and the double storage, the new btrees are expected to use 8*1.5*2 = 24 bytes per record, or 33.3% as much memory as the AVL trees (this is for the purposes of storing metaslab range trees; for other purposes, like scrubs, they use ~50% as much memory). We reduced the size of the payload in the range segments by teaching range trees about starting offsets and shifts; since metaslabs have a fixed starting offset, and they all operate in terms of disk sectors, we can store the ranges using 4-byte integers as long as the size of the metaslab divided by the sector size is less than 2^32. For 512-byte sectors, this is a 2^41 (or 2TB) metaslab, which with the default settings corresponds to a 256PB disk. 4k sector disks can handle metaslabs up to 2^46 bytes, or 2^63 byte disks. Since we do not anticipate disks of this size in the near future, there should be almost no cases where metaslabs need 64-byte integers to store their ranges. We do still have the capability to store 64-byte integer ranges to account for cases where we are storing per-vdev (or per-dnode) trees, which could reasonably go above the limits discussed. We also do not store fill information in the compact version of the node, since it is only used for sorted scrub. We also optimized the metaslab loading process in various other ways to offset some inefficiencies in the btree model. While individual operations (find, insert, remove_from) are faster for the btree than they are for the avl tree, remove usually requires a find operation, while in the AVL tree model the element itself suffices. Some clever changes actually caused an overall speedup in metaslab loading; we use approximately 40% less cpu to load metaslabs in our tests on Illumos. Another memory and performance optimization was achieved by changing what is stored in the size-sorted trees. When a disk is heavily fragmented, the df algorithm used by default in ZFS will almost always find a number of small regions in its initial cursor-based search; it will usually only fall back to the size-sorted tree to find larger regions. If we increase the size of the cursor-based search slightly, and don't store segments that are smaller than a tunable size floor in the size-sorted tree, we can further cut memory usage down to below 20% of what the AVL trees store. This also results in further reductions in CPU time spent loading metaslabs. The 16KiB size floor was chosen because it results in substantial memory usage reduction while not usually resulting in situations where we can't find an appropriate chunk with the cursor and are forced to use an oversized chunk from the size-sorted tree. In addition, even if we do have to use an oversized chunk from the size-sorted tree, the chunk would be too small to use for ZIL allocations, so it isn't as big of a loss as it might otherwise be. And often, more small allocations will follow the initial one, and the cursor search will now find the remainder of the chunk we didn't use all of and use it for subsequent allocations. Practical testing has shown little or no change in fragmentation as a result of this change. If the size-sorted tree becomes empty while the offset sorted one still has entries, it will load all the entries from the offset sorted tree and disregard the size floor until it is unloaded again. This operation occurs rarely with the default setting, only on incredibly thoroughly fragmented pools. There are some other small changes to zdb to teach it to handle btrees, but nothing major. Reviewed-by: George Wilson <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed by: Sebastien Roy [email protected] Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Closes #9181
* Device removal of indirect vdev panics the kernelloli10K2019-09-161-0/+4
| | | | | | | | | | This commit fixes a NULL pointer dereference triggered in spa_vdev_remove_top_check() by trying to "zpool remove" an indirect vdev. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: loli10K <[email protected]> Closes #9327
* Add subcommand to wait for background zfs activity to completeJohn Gallagher2019-09-131-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently the best way to wait for the completion of a long-running operation in a pool, like a scrub or device removal, is to poll 'zpool status' and parse its output, which is neither efficient nor convenient. This change adds a 'wait' subcommand to the zpool command. When invoked, 'zpool wait' will block until a specified type of background activity completes. Currently, this subcommand can wait for any of the following: - Scrubs or resilvers to complete - Devices to initialized - Devices to be replaced - Devices to be removed - Checkpoints to be discarded - Background freeing to complete For example, a scrub that is in progress could be waited for by running zpool wait -t scrub <pool> This also adds a -w flag to the attach, checkpoint, initialize, replace, remove, and scrub subcommands. When used, this flag makes the operations kicked off by these subcommands synchronous instead of asynchronous. This functionality is implemented using a new ioctl. The type of activity to wait for is provided as input to the ioctl, and the ioctl blocks until all activity of that type has completed. An ioctl was used over other methods of kernel-userspace communiction primarily for the sake of portability. Porting Notes: This is ported from Delphix OS change DLPX-44432. The following changes were made while porting: - Added ZoL-style ioctl input declaration. - Reorganized error handling in zpool_initialize in libzfs to integrate better with changes made for TRIM support. - Fixed check for whether a checkpoint discard is in progress. Previously it also waited if the pool had a checkpoint, instead of just if a checkpoint was being discarded. - Exposed zfs_initialize_chunk_size as a ZoL-style tunable. - Updated more existing tests to make use of new 'zpool wait' functionality, tests that don't exist in Delphix OS. - Used existing ZoL tunable zfs_scan_suspend_progress, together with zinject, in place of a new tunable zfs_scan_max_blks_per_txg. - Added support for a non-integral interval argument to zpool wait. Future work: ZoL has support for trimming devices, which Delphix OS does not. In the future, 'zpool wait' could be extended to add the ability to wait for trim operations to complete. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: John Kennedy <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: John Gallagher <[email protected]> Closes #9162
* Enable compiler to typecheck loggingMatthew Macy2019-09-121-3/+4
| | | | | | | | | | Annotate spa logging declarations with printflike Workaround gcc bug (non disable-able warning) by replacing "" with " " Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matt Macy <[email protected]> Closes #9316
* OpenZFS restructuring - move linux tracing code to platform directoriesMatthew Macy2019-09-111-1/+1
| | | | | | | | | | | Move Linux specific tracing headers and source to platform directories and update the build system. Reviewed-by: Allan Jude <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Reviewed by: Brad Lewis <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matt Macy <[email protected]> Closes #9290
* Make module tunables cross platformMatthew Macy2019-09-051-11/+5
| | | | | | | | | | | Adds ZFS_MODULE_PARAM to abstract module parameter setting to operating systems other than Linux. Reviewed-by: Jorgen Lundman <[email protected]> Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matt Macy <[email protected]> Signed-off-by: Ryan Moeller <[email protected]> Closes #9230
* Log Spacemap ProjectSerapheim Dimitropoulos2019-07-161-7/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | = Motivation At Delphix we've seen a lot of customer systems where fragmentation is over 75% and random writes take a performance hit because a lot of time is spend on I/Os that update on-disk space accounting metadata. Specifically, we seen cases where 20% to 40% of sync time is spend after sync pass 1 and ~30% of the I/Os on the system is spent updating spacemaps. The problem is that these pools have existed long enough that we've touched almost every metaslab at least once, and random writes scatter frees across all metaslabs every TXG, thus appending to their spacemaps and resulting in many I/Os. To give an example, assuming that every VDEV has 200 metaslabs and our writes fit within a single spacemap block (generally 4K) we have 200 I/Os. Then if we assume 2 levels of indirection, we need 400 additional I/Os and since we are talking about metadata for which we keep 2 extra copies for redundancy we need to triple that number, leading to a total of 1800 I/Os per VDEV every TXG. We could try and decrease the number of metaslabs so we have less I/Os per TXG but then each metaslab would cover a wider range on disk and thus would take more time to be loaded in memory from disk. In addition, after it's loaded, it's range tree would consume more memory. Another idea would be to just increase the spacemap block size which would allow us to fit more entries within an I/O block resulting in fewer I/Os per metaslab and a speedup in loading time. The problem is still that we don't deal with the number of I/Os going up as the number of metaslabs is increasing and the fact is that we generally write a lot to a few metaslabs and a little to the rest of them. Thus, just increasing the block size would actually waste bandwidth because we won't be utilizing our bigger block size. = About this patch This patch introduces the Log Spacemap project which provides the solution to the above problem while taking into account all the aforementioned tradeoffs. The details on how it achieves that can be found in the references sections below and in the code (see Big Theory Statement in spa_log_spacemap.c). Even though the change is fairly constraint within the metaslab and lower-level SPA codepaths, there is a side-change that is user-facing. The change is that VDEV IDs from VDEV holes will no longer be reused. To give some background and reasoning for this, when a log device is removed and its VDEV structure was replaced with a hole (or was compacted; if at the end of the vdev array), its vdev_id could be reused by devices added after that. Now with the pool-wide space maps recording the vdev ID, this behavior can cause problems (e.g. is this entry referring to a segment in the new vdev or the removed log?). Thus, to simplify things the ID reuse behavior is gone and now vdev IDs for top-level vdevs are truly unique within a pool. = Testing The illumos implementation of this feature has been used internally for a year and has been in production for ~6 months. For this patch specifically there don't seem to be any regressions introduced to ZTS and I have been running zloop for a week without any related problems. = Performance Analysis (Linux Specific) All performance results and analysis for illumos can be found in the links of the references. Redoing the same experiments in Linux gave similar results. Below are the specifics of the Linux run. After the pool reached stable state the percentage of the time spent in pass 1 per TXG was 64% on average for the stock bits while the log spacemap bits stayed at 95% during the experiment (graph: sdimitro.github.io/img/linux-lsm/PercOfSyncInPassOne.png). Sync times per TXG were 37.6 seconds on average for the stock bits and 22.7 seconds for the log spacemap bits (related graph: sdimitro.github.io/img/linux-lsm/SyncTimePerTXG.png). As a result the log spacemap bits were able to push more TXGs, which is also the reason why all graphs quantified per TXG have more entries for the log spacemap bits. Another interesting aspect in terms of txg syncs is that the stock bits had 22% of their TXGs reach sync pass 7, 55% reach sync pass 8, and 20% reach 9. The log space map bits reached sync pass 4 in 79% of their TXGs, sync pass 7 in 19%, and sync pass 8 at 1%. This emphasizes the fact that not only we spend less time on metadata but we also iterate less times to convergence in spa_sync() dirtying objects. [related graphs: stock- sdimitro.github.io/img/linux-lsm/NumberOfPassesPerTXGStock.png lsm- sdimitro.github.io/img/linux-lsm/NumberOfPassesPerTXGLSM.png] Finally, the improvement in IOPs that the userland gains from the change is approximately 40%. There is a consistent win in IOPS as you can see from the graphs below but the absolute amount of improvement that the log spacemap gives varies within each minute interval. sdimitro.github.io/img/linux-lsm/StockVsLog3Days.png sdimitro.github.io/img/linux-lsm/StockVsLog10Hours.png = Porting to Other Platforms For people that want to port this commit to other platforms below is a list of ZoL commits that this patch depends on: Make zdb results for checkpoint tests consistent db587941c5ff6dea01932bb78f70db63cf7f38ba Update vdev_is_spacemap_addressable() for new spacemap encoding 419ba5914552c6185afbe1dd17b3ed4b0d526547 Simplify spa_sync by breaking it up to smaller functions 8dc2197b7b1e4d7ebc1420ea30e51c6541f1d834 Factor metaslab_load_wait() in metaslab_load() b194fab0fb6caad18711abccaff3c69ad8b3f6d3 Rename range_tree_verify to range_tree_verify_not_present df72b8bebe0ebac0b20e0750984bad182cb6564a Change target size of metaslabs from 256GB to 16GB c853f382db731e15a87512f4ef1101d14d778a55 zdb -L should skip leak detection altogether 21e7cf5da89f55ce98ec1115726b150e19eefe89 vs_alloc can underflow in L2ARC vdevs 7558997d2f808368867ca7e5234e5793446e8f3f Simplify log vdev removal code 6c926f426a26ffb6d7d8e563e33fc176164175cb Get rid of space_map_update() for ms_synced_length 425d3237ee88abc53d8522a7139c926d278b4b7f Introduce auxiliary metaslab histograms 928e8ad47d3478a3d5d01f0dd6ae74a9371af65e Error path in metaslab_load_impl() forgets to drop ms_sync_lock 8eef997679ba54547f7d361553d21b3291f41ae7 = References Background, Motivation, and Internals of the Feature - OpenZFS 2017 Presentation: youtu.be/jj2IxRkl5bQ - Slides: slideshare.net/SerapheimNikolaosDim/zfs-log-spacemaps-project Flushing Algorithm Internals & Performance Results (Illumos Specific) - Blogpost: sdimitro.github.io/post/zfs-lsm-flushing/ - OpenZFS 2018 Presentation: youtu.be/x6D2dHRjkxw - Slides: slideshare.net/SerapheimNikolaosDim/zfs-log-spacemap-flushing-algorithm Upstream Delphix Issues: DLPX-51539, DLPX-59659, DLPX-57783, DLPX-61438, DLPX-41227, DLPX-59320 DLPX-63385 Reviewed-by: Sean Eric Fagan <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8442
* panic in removal_remap test on 4K devicesMatthew Ahrens2019-06-131-7/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the zfs_remove_max_segment tunable is changed to be not a multiple of the sector size, then the device removal code will malfunction and try to create mappings that are smaller than one sector, leading to a panic. On debug bits this assertion will fail in spa_vdev_copy_segment(): ASSERT3U(DVA_GET_ASIZE(&dst), ==, size); On nondebug, the system panics with a stack like: metaslab_free_concrete() metaslab_free_impl() metaslab_free_impl_cb() vdev_indirect_remap() free_from_removing_vdev() metaslab_free_impl() metaslab_free_dva() metaslab_free() Fortunately, the default for zfs_remove_max_segment is 1MB, so this can't occur by default. We hit it during this test because removal_remap.ksh changes zfs_remove_max_segment to 1KB. When testing on 4KB-sector disks, we hit the bug. This change makes the zfs_remove_max_segment tunable more robust, automatically rounding it up to a multiple of the sector size. We also turn some key assertions into VERIFY's so that similar bugs would be caught before they are encoded on disk (and thus avoid a panic-reboot-loop). Reviewed-by: Sean Eric Fagan <[email protected]> Reviewed-by: Pavel Zakharov <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Sebastien Roy <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> External-issue: DLPX-61342 Closes #8893
* ztest: dmu_tx_assign() gets ENOSPC in spa_vdev_remove_thread()Matthew Ahrens2019-06-131-1/+1
| | | | | | | | | | | | | | | | | | | | | When running zloop, we occasionally see the following crash: dmu_tx_assign(tx, TXG_WAIT) == 0 (0x1c == 0) ASSERT at ../../module/zfs/vdev_removal.c:1507:spa_vdev_remove_thread()/sbin/ztest(+0x89c3)[0x55faf567b9c3] The error value 0x1c is ENOSPC. The transaction used by spa_vdev_remove_thread() should not be able to fail due to being out of space. i.e. we should not call dmu_tx_hold_space(). This will allow the removal thread to schedule its work even when the pool is low on space. The "slop space" will provide enough free space to sync out the txg. Reviewed-by: Igor Kozhukhov <[email protected]> Reviewed-by: Paul Dagnelie <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> External-issue: DLPX-37853 Closes #8889
* Restrict kstats and print real pointersSara Hartse2019-04-041-1/+1
| | | | | | | | | | | | | | | There are several places where we use zfs_dbgmsg and %p to print pointers. In the Linux kernel, these values obfuscated to prevent information leaks which means the pointers aren't very useful for debugging crash dumps. We decided to restrict the permissions of dbgmsg (and some other kstats while we were at it) and print pointers with %px in zfs_dbgmsg as well as spl_dumpstack Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: John Gallagher <[email protected]> Signed-off-by: sara hartse <[email protected]> Closes #8467 Closes #8476
* Add TRIM supportBrian Behlendorf2019-03-291-4/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | UNMAP/TRIM support is a frequently-requested feature to help prevent performance from degrading on SSDs and on various other SAN-like storage back-ends. By issuing UNMAP/TRIM commands for sectors which are no longer allocated the underlying device can often more efficiently manage itself. This TRIM implementation is modeled on the `zpool initialize` feature which writes a pattern to all unallocated space in the pool. The new `zpool trim` command uses the same vdev_xlate() code to calculate what sectors are unallocated, the same per- vdev TRIM thread model and locking, and the same basic CLI for a consistent user experience. The core difference is that instead of writing a pattern it will issue UNMAP/TRIM commands for those extents. The zio pipeline was updated to accommodate this by adding a new ZIO_TYPE_TRIM type and associated spa taskq. This new type makes is straight forward to add the platform specific TRIM/UNMAP calls to vdev_disk.c and vdev_file.c. These new ZIO_TYPE_TRIM zios are handled largely the same way as ZIO_TYPE_READs or ZIO_TYPE_WRITEs. This makes it possible to largely avoid changing the pipieline, one exception is that TRIM zio's may exceed the 16M block size limit since they contain no data. In addition to the manual `zpool trim` command, a background automatic TRIM was added and is controlled by the 'autotrim' property. It relies on the exact same infrastructure as the manual TRIM. However, instead of relying on the extents in a metaslab's ms_allocatable range tree, a ms_trim tree is kept per metaslab. When 'autotrim=on', ranges added back to the ms_allocatable tree are also added to the ms_free tree. The ms_free tree is then periodically consumed by an autotrim thread which systematically walks a top level vdev's metaslabs. Since the automatic TRIM will skip ranges it considers too small there is value in occasionally running a full `zpool trim`. This may occur when the freed blocks are small and not enough time was allowed to aggregate them. An automatic TRIM and a manual `zpool trim` may be run concurrently, in which case the automatic TRIM will yield to the manual TRIM. Reviewed-by: Jorgen Lundman <[email protected]> Reviewed-by: Tim Chase <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Contributions-by: Saso Kiselkov <[email protected]> Contributions-by: Tim Chase <[email protected]> Contributions-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #8419 Closes #598
* Fix vd_path and error in spa_vdev_remove()Igor K2019-03-221-5/+12
| | | | | | | | | | | Make a local copy of the vd_path and preserve the removal error for use in spa_history_log_internal(). This is required because after spa_vdev_exit() there is nothing preventing the vdev state from changing. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Tom Caputi <[email protected]> Signed-off-by: Igor Kozhukhov <[email protected]> Closes #8522
* Get rid of space_map_update() for ms_synced_lengthSerapheim Dimitropoulos2019-02-121-37/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Initially, metaslabs and space maps used to be the same thing in ZFS. Later, we started differentiating them by referring to the space map as the on-disk state of the metaslab, making the metaslab a higher-level concept that is metadata that deals with space accounting. Today we've managed to split that code furthermore, with the space map being its own on-disk data structure used in areas of ZFS besides metaslabs (e.g. the vdev-wide space maps used for zpool checkpoint or vdev removal features). This patch refactors the space map code to further split the space map code from the metaslab code. It does so by getting rid of the idea that the space map can have a different in-core and on-disk length (sm_length vs smp_length) which is something that is only used for the metaslab code, and other consumers of space maps just have to deal with. Instead, this patch introduces changes that move the old in-core length of the metaslab's space map to the metaslab structure itself (see ms_synced_length field) while making the space map code only care about the actual space map's length on-disk. The result of this is that space map consumers no longer have to deal with syncing two different lengths for the same structure (e.g. space_map_update() goes away) while metaslab specific behavior stays within the metaslab code. Specifically, the ms_synced_length field keeps track of the amount of data metaslab_load() can read from the metaslab's space map while working concurrently with metaslab_sync() that may be appending to that same space map. As a side note, the patch also adds a few comments around the metaslab code documenting some assumptions and expected behavior. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed by: Pavel Zakharov <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8328
* Simplify log vdev removal codeSerapheim Dimitropoulos2019-01-311-6/+10
| | | | | | | | | | Get rid of the majority metaslab metadata when removing log vdevs in spa_vdev_remove_log() with a call to metaslab_fini() instead of duplicating a lot of that in vdev_remove_empty_log(). Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8347
* Simplify spa_sync by breaking it up to smaller functionsSerapheim Dimitropoulos2019-01-181-0/+3
| | | | | | | | | | | | The point of this refactoring is to break the high-level conceptual steps of spa_sync() to their own helper functions. In general large functions can enhance readability if structured well, but in this case the amount of conceptual steps taken could use the help of helper functions. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8293
* zfs initialize performance enhancementsGeorge Wilson2019-01-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PROBLEM ======== When invoking "zpool initialize" on a pool the command will create a thread to initialize each disk. Unfortunately, it does this serially across many transaction groups which can result in commands taking a long time to return to the user and may appear hung. The same thing is true when trying to suspend/cancel the operation. SOLUTION ========= This change refactors the way we invoke the initialize interface to ensure we can start or stop the intialization in just a few transaction groups. When stopping or cancelling a vdev initialization perform it in two phases. First signal each vdev initialization thread that it should exit, then after all threads have been signaled wait for them to exit. On a pool with 40 leaf vdevs this reduces the vdev initialize stop/cancel time from ~10 minutes to under a second. The reason for this is spa_vdev_initialize() no longer needs to wait on multiple full TXGs per leaf vdev being stopped. This commit additionally adds some missing checks for the passed "initialize_vdevs" input nvlist. The contents of the user provided input "initialize_vdevs" nvlist must be validated to ensure all values are uint64s. This is done in zfs_ioc_pool_initialize() in order to keep all of these checks in a single location. Updated the innvl and outnvl comments to match the formatting used for all other new sytle ioctls. Reviewed by: Matt Ahrens <[email protected]> Reviewed-by: loli10K <[email protected]> Reviewed-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: George Wilson <[email protected]> Closes #8230
* OpenZFS 9102 - zfs should be able to initialize storage devicesGeorge Wilson2019-01-071-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PROBLEM ======== The first access to a block incurs a performance penalty on some platforms (e.g. AWS's EBS, VMware VMDKs). Therefore we recommend that volumes are "thick provisioned", where supported by the platform (VMware). This can create a large delay in getting a new virtual machines up and running (or adding storage to an existing Engine). If the thick provision step is omitted, write performance will be suboptimal until all blocks on the LUN have been written. SOLUTION ========= This feature introduces a way to 'initialize' the disks at install or in the background to make sure we don't incur this first read penalty. When an entire LUN is added to ZFS, we make all space available immediately, and allow ZFS to find unallocated space and zero it out. This works with concurrent writes to arbitrary offsets, ensuring that we don't zero out something that has been (or is in the middle of being) written. This scheme can also be applied to existing pools (affecting only free regions on the vdev). Detailed design: - new subcommand:zpool initialize [-cs] <pool> [<vdev> ...] - start, suspend, or cancel initialization - Creates new open-context thread for each vdev - Thread iterates through all metaslabs in this vdev - Each metaslab: - select a metaslab - load the metaslab - mark the metaslab as being zeroed - walk all free ranges within that metaslab and translate them to ranges on the leaf vdev - issue a "zeroing" I/O on the leaf vdev that corresponds to a free range on the metaslab we're working on - continue until all free ranges for this metaslab have been "zeroed" - reset/unmark the metaslab being zeroed - if more metaslabs exist, then repeat above tasks. - if no more metaslabs, then we're done. - progress for the initialization is stored on-disk in the vdev’s leaf zap object. The following information is stored: - the last offset that has been initialized - the state of the initialization process (i.e. active, suspended, or canceled) - the start time for the initialization - progress is reported via the zpool status command and shows information for each of the vdevs that are initializing Porting notes: - Added zfs_initialize_value module parameter to set the pattern written by "zpool initialize". - Added zfs_vdev_{initializing,removal}_{min,max}_active module options. Authored by: George Wilson <[email protected]> Reviewed by: John Wren Kennedy <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: Pavel Zakharov <[email protected]> Reviewed by: Prakash Surya <[email protected]> Reviewed by: loli10K <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Approved by: Richard Lowe <[email protected]> Signed-off-by: Tim Chase <[email protected]> Ported-by: Tim Chase <[email protected]> OpenZFS-issue: https://www.illumos.org/issues/9102 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/c3963210eb Closes #8230
* Fix ztest deadlock in spa_vdev_remove()Tom Caputi2018-12-041-12/+19
| | | | | | | | | | | | | | This patch corrects an issue where spa_vdev_remove() would call spa_history_log_internal() while holding the spa config lock. This function may decide to block until the next txg if the current one seems too full. However, since the thread is holding the config log, the txg sync thread cannot progress and the system ends up deadlocked. This patch simply moves all calls to spa_history_log_internal() outside of the config lock. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #8162
* Detect IO errors during device removalBrian Behlendorf2018-12-041-11/+89
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Detect IO errors during device removal While device removal cannot verify the checksums of individual blocks during device removal, it can reasonably detect hard IO errors from the leaf vdevs. Failure to perform this error checking can result in device removal completing successfully, but moving no data which will permanently corrupt the pool. Situation 1: faulted/degraded vdevs In the configuration shown below, the removal of mirror-0 will permanently corrupt the pool. Device removal will preferentially copy data from 'vdev1 -> vdev3' and from 'vdev2 -> vdev4'. Which in this case will result in nothing being copied since one vdev in each of those groups in unavailable. However, device removal will complete successfully since all IO errors are ignored. tank DEGRADED 0 0 0 mirror-0 DEGRADED 0 0 0 /var/tmp/vdev1 FAULTED 0 0 0 external fault /var/tmp/vdev2 ONLINE 0 0 0 mirror-1 DEGRADED 0 0 0 /var/tmp/vdev3 ONLINE 0 0 0 /var/tmp/vdev4 FAULTED 0 0 0 external fault This issue is resolved by updating the source child selection logic to exclude unreadable leaf vdevs. Additionally, unwritable destination child vdevs which can never succeed are skipped to prevent generating a large number of write IO errors. Situation 2: individual hard IO errors During removal if an unexpected hard IO error is encountered when either reading or writing the child vdev the entire removal operation is cancelled. While it may be possible to reconstruct the data after removal that cannot be guaranteed. The only strictly safe thing to do is to cancel the removal. As a future improvement we may want to instead suspend the removal process and allow the damaged region to be retried. But that work is left for another time, hard IO errors during the removal process are expected to be exceptionally rare. Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Tony Hutter <[email protected]> Reviewed-by: Tom Caputi <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #6900 Closes #8161
* Fix consistency of ztest_device_removal_activeTom Caputi2018-11-281-8/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | ztest currently uses the boolean flag ztest_device_removal_active to protect some tests that may not run successfully if they occur at the same time as ztest_device_removal(). Unfortunately, in the event that ztest is in the middle of a device removal when it decides to issue a SIGKILL, the device removal will be automatically restarted (without setting the flag) when the pool is re-imported on the next run. This patch corrects this by ensuring that any in-progress removals are completed before running further tests after the re-import. This patch also makes a few small changes to prevent race conditions involving the creation and destruction of spa->spa_vdev_removal, since this field is not protected by any locks. Some checks that may run concurrently with setting / unsetting this field have been updated to check spa->spa_removing_phys.sr_state instead. The most significant change here is that spa_removal_get_stats() no longer accounts for in-flight work done, since that could result in a NULL pointer dereference. Reviewed by: Matthew Ahrens <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #8105
* Remove races from scrub / resilver testsTom Caputi2018-11-281-5/+5
| | | | | | | | | | | | | | | | | | | | | | Currently, several tests in the ZFS Test Suite that attempt to test scrub and resilver behavior occasionally fail. A big reason for this is that these tests use a combination of zinject and zfs_scan_vdev_limit to attempt to slow these operations enough to verify their test commands. This method works most of the time, but provides no guarantees and leads to flaky behavior. This patch adds a new tunable, zfs_scan_suspend_progress, that ensures that scans make no progress, guaranteeing that tests can be run without racing. This patch also changes zfs_remove_max_bytes_pause to match this new tunable. This provides some consistency between these two similar tunables and ensures that the tunable will not misbehave on 32-bit systems. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Giuseppe Di Natale <[email protected]> Reviewed-by: Tony Hutter <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #8111
* Fix vdev removal finishing raceTom Caputi2018-11-071-9/+6
| | | | | | | | | | | | | This patch fixes a race condition where the end of vdev_remove_replace_with_indirect(), which holds svr_lock, would race against spa_vdev_removal_destroy(), which destroys the same lock and is called asynchronously via dsl_sync_task_nowait(). Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Issue #6900 Closes #8083
* Improved error handling for extreme rewindsBrian Behlendorf2018-10-121-4/+11
| | | | | | | | | | | | | | | | | | | | | | | The vdev_checkpoint_sm_object(), vdev_obsolete_sm_object(), and vdev_obsolete_counts_are_precise() functions assume that the only way a zap_lookup() can fail is if the requested entry is missing. While this is the most common cause, it's not the only cause. Attemping to access a damaged ZAP will result in other errors. The most likely scenario for accessing a damaged ZAP is during an extreme rewind pool import. Under these conditions the pool is expected to contain damaged objects and the import code was updated to handle this gracefully. Getting an ECKSUM error from these ZAPs after the pool in import a far less likely, therefore the behavior for call paths was not modified. Reviewed-by: Tim Chase <[email protected]> Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #7809 Closes #7921
* Pool allocation classesDon Brady2018-09-051-6/+32
| | | | | | | | | | | | | | | | | | | | Allocation Classes add the ability to have allocation classes in a pool that are dedicated to serving specific block categories, such as DDT data, metadata, and small file blocks. A pool can opt-in to this feature by adding a 'special' or 'dedup' top-level VDEV. Reviewed by: Pavel Zakharov <[email protected]> Reviewed-by: Richard Laager <[email protected]> Reviewed-by: Alek Pinchuk <[email protected]> Reviewed-by: Håkan Johansson <[email protected]> Reviewed-by: Andreas Dilger <[email protected]> Reviewed-by: DHE <[email protected]> Reviewed-by: Richard Elling <[email protected]> Reviewed-by: Gregor Kopka <[email protected]> Reviewed-by: Kash Pande <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matthew Ahrens <[email protected]> Signed-off-by: Don Brady <[email protected]> Closes #5182
* OpenZFS 9112 - Improve allocation performance on high-end systemsPaul Dagnelie2018-07-311-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Overview ======== We parallelize the allocation process by creating the concept of "allocators". There are a certain number of allocators per metaslab group, defined by the value of a tunable at pool open time. Each allocator for a given metaslab group has up to 2 active metaslabs; one "primary", and one "secondary". The primary and secondary weight mean the same thing they did in in the pre-allocator world; primary metaslabs are used for most allocations, secondary metaslabs are used for ditto blocks being allocated in the same metaslab group. There is also the CLAIM weight, which has been separated out from the other weights, but that is less important to understanding the patch. The active metaslabs for each allocator are moved from their normal place in the metaslab tree for the group to the back of the tree. This way, they will not be selected for use by other allocators searching for new metaslabs unless all the passive metaslabs are unsuitable for allocations. If that does happen, the allocators will "steal" from each other to ensure that IOs don't fail until there is truly no space left to perform allocations. In addition, the alloc queue for each metaslab group has been broken into a separate queue for each allocator. We don't want to dramatically increase the number of inflight IOs on low-end systems, because it can significantly increase txg times. On the other hand, we want to ensure that there are enough IOs for each allocator to allow for good coalescing before sending the IOs to the disk. As a result, we take a compromise path; each allocator's alloc queue max depth starts at a certain value for every txg. Every time an IO completes, we increase the max depth. This should hopefully provide a good balance between the two failure modes, while not dramatically increasing complexity. We also parallelize the spa_alloc_tree and spa_alloc_lock, which cause very similar contention when selecting IOs to allocate. This parallelization uses the same allocator scheme as metaslab selection. Performance Results =================== Performance improvements from this change can vary significantly based on the number of CPUs in the system, whether or not the system has a NUMA architecture, the speed of the drives, the values for the various tunables, and the workload being performed. For an fio async sequential write workload on a 24 core NUMA system with 256 GB of RAM and 8 128 GB SSDs, there is a roughly 25% performance improvement. Future Work =========== Analysis of the performance of the system with this patch applied shows that a significant new bottleneck is the vdev disk queues, which also need to be parallelized. Prototyping of this change has occurred, and there was a performance improvement, but more work needs to be done before its stability has been verified and it is ready to be upstreamed. Authored by: Paul Dagnelie <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Serapheim Dimitropoulos <[email protected]> Reviewed by: Alexander Motin <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Approved by: Gordon Ross <[email protected]> Ported-by: Paul Dagnelie <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Porting Notes: * Fix reservation test failures by increasing tolerance. OpenZFS-issue: https://illumos.org/issues/9112 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/3f3cc3c3 Closes #7682
* OpenZFS 9166 - zfs storage pool checkpointSerapheim Dimitropoulos2018-06-261-21/+64
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Details about the motivation of this feature and its usage can be found in this blogpost: https://sdimitro.github.io/post/zpool-checkpoint/ A lightning talk of this feature can be found here: https://www.youtube.com/watch?v=fPQA8K40jAM Implementation details can be found in big block comment of spa_checkpoint.c Side-changes that are relevant to this commit but not explained elsewhere: * renames members of "struct metaslab trees to be shorter without losing meaning * space_map_{alloc,truncate}() accept a block size as a parameter. The reason is that in the current state all space maps that we allocate through the DMU use a global tunable (space_map_blksz) which defauls to 4KB. This is ok for metaslab space maps in terms of bandwirdth since they are scattered all over the disk. But for other space maps this default is probably not what we want. Examples are device removal's vdev_obsolete_sm or vdev_chedkpoint_sm from this review. Both of these have a 1:1 relationship with each vdev and could benefit from a bigger block size. Porting notes: * The part of dsl_scan_sync() which handles async destroys has been moved into the new dsl_process_async_destroys() function. * Remove "VERIFY(!(flags & FWRITE))" in "kernel.c" so zhack can write to block device backed pools. * ZTS: * Fix get_txg() in zpool_sync_001_pos due to "checkpoint_txg". * Don't use large dd block sizes on /dev/urandom under Linux in checkpoint_capacity. * Adopt Delphix-OS's setting of 4 (spa_asize_inflation = SPA_DVAS_PER_BP + 1) for the checkpoint_capacity test to speed its attempts to fill the pool * Create the base and nested pools with sync=disabled to speed up the "setup" phase. * Clear labels in test pool between checkpoint tests to avoid duplicate pool issues. * The import_rewind_device_replaced test has been marked as "known to fail" for the reasons listed in its DISCLAIMER. * New module parameters: zfs_spa_discard_memory_limit, zfs_remove_max_bytes_pause (not documented - debugging only) vdev_max_ms_count (formerly metaslabs_per_vdev) vdev_min_ms_count Authored by: Serapheim Dimitropoulos <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: John Kennedy <[email protected]> Reviewed by: Dan Kimmel <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Approved by: Richard Lowe <[email protected]> Ported-by: Tim Chase <[email protected]> Signed-off-by: Tim Chase <[email protected]> OpenZFS-issue: https://illumos.org/issues/9166 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7159fdb8 Closes #7570
* Update build system and packagingBrian Behlendorf2018-05-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Minimal changes required to integrate the SPL sources in to the ZFS repository build infrastructure and packaging. Build system and packaging: * Renamed SPL_* autoconf m4 macros to ZFS_*. * Removed redundant SPL_* autoconf m4 macros. * Updated the RPM spec files to remove SPL package dependency. * The zfs package obsoletes the spl package, and the zfs-kmod package obsoletes the spl-kmod package. * The zfs-kmod-devel* packages were updated to add compatibility symlinks under /usr/src/spl-x.y.z until all dependent packages can be updated. They will be removed in a future release. * Updated copy-builtin script for in-kernel builds. * Updated DKMS package to include the spl.ko. * Updated stale AUTHORS file to include all contributors. * Updated stale COPYRIGHT and included the SPL as an exception. * Renamed README.markdown to README.md * Renamed OPENSOLARIS.LICENSE to LICENSE. * Renamed DISCLAIMER to NOTICE. Required code changes: * Removed redundant HAVE_SPL macro. * Removed _BOOT from nvpairs since it doesn't apply for Linux. * Initial header cleanup (removal of empty headers, refactoring). * Remove SPL repository clone/build from zimport.sh. * Use of DEFINE_RATELIMIT_STATE and DEFINE_SPINLOCK removed due to build issues when forcing C99 compilation. * Replaced legacy ACCESS_ONCE with READ_ONCE. * Include needed headers for `current` and `EXPORT_SYMBOL`. Reviewed-by: Tony Hutter <[email protected]> Reviewed-by: Olaf Faaland <[email protected]> Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: Pavel Zakharov <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> TEST_ZIMPORT_SKIP="yes" Closes #7556
* OpenZFS 9486 - reduce memory used by device removal on fragmented poolsMatthew Ahrens2018-05-241-23/+190
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Device removal allocates a new location for each allocated segment on the disk that's being removed. Each allocation results in one entry in the mapping table, which maps from old location + length to new location. When a fragmented disk is removed, this can result in a large number of mapping entries, and thus a large amount of memory consumed by the mapping table. In the worst real-world cases, we've seen around 1GB of RAM per 1TB of storage removed. We can improve on this situation by allocating larger segments, which span across both allocated and free regions of the device being removed. By including free regions in the allocation (and thus mapping), we reduce the number of mapping entries. For example, if we have a 4K allocation followed by 1K free and then 4K allocated, we would allocate 4+1+4 = 9KB, and then move the entire region (including allocated and free parts). In this case we used one mapping where previously we would have used two, but often the ratio is much higher (up to 20:1 in real-world use). We then need to mark the regions that were free on the removing device as free in the new locations, and also obsolete in the mapping entry. This method preserves the fragmentation of the removing device, rather than consolidating its allocated space into a small number of chunks where possible. But it results in drastic reduction of memory used by the mapping table - around 20x in the most-fragmented cases. In the most fragmented real-world cases, this reduces memory used by the mapping from ~1GB to ~50MB of RAM per 1TB of storage removed. Less fragmented cases will typically also see around 50-100MB of RAM per 1TB of storage. Porting notes: * Add the following as module parameters: * zfs_condense_indirect_vdevs_enable * zfs_condense_max_obsolete_bytes * Document the following module parameters: * zfs_condense_indirect_vdevs_enable * zfs_condense_max_obsolete_bytes * zfs_condense_min_mapping_bytes Authored by: Matthew Ahrens <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Ported-by: Tim Chase <[email protected]> Signed-off-by: Tim Chase <[email protected]> OpenZFS-issue: https://illumos.org/issues/9486 OpenZFS-commit: https://github.com/ahrens/illumos/commit/07152e142e44c External-issue: DLPX-57962 Closes #7536
* OpenZFS 9434 - Speculative prefetch is blocked by device removal codeAlexander Motin2018-04-301-0/+1
| | | | | | | | | | | | | | | | | | | | Device removal code does not set spa_indirect_vdevs_loaded for pools that never experienced device removal. At least one visual consequence of it is completely blocked speculative prefetcher. This patch sets the variable in such situations. Authored by: Alexander Motin <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: Prashanth Sreenivasa <[email protected]> Reviewed-by: George Melikov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Tim Chase <[email protected]> Approved by: Matt Ahrens <[email protected]> Ported-by: Giuseppe Di Natale <[email protected]> OpenZFS-issue: https://www.illumos.org/issues/9434 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/16127b627b Closes #7480
* OpenZFS 9290 - device removal reduces redundancy of mirrorsMatthew Ahrens2018-04-141-166/+196
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mirrors are supposed to provide redundancy in the face of whole-disk failure and silent damage (e.g. some data on disk is not right, but ZFS hasn't detected the whole device as being broken). However, the current device removal implementation bypasses some of the mirror's redundancy. Note that in no case is incorrect data returned, but we might get a checksum error when we should have been able to find the right data. There are two underlying problems: 1. When we remove a mirror device, we only read one side of the mirror. Since we can't verify the checksum, this side may be silently bad, but the good data is on the other side of the mirror (which we didn't read). This can cause the removal to "bake in" the busted data – all copies of the data in the new location are the same, busted version, while we left the good version behind. The fix for this is to read and copy both sides of the mirror. If the old and new vdevs are mirrors, we will read both sides of the old mirror, and write each copy to the corresponding side of the new mirror. (If the old and new vdevs have a different number of children, we will do this as best as possible.) Even though we aren't verifying checksums, this ensures that as long as there's a good copy of the data, we'll have a good copy after the removal, even if there's silent damage to one side of the mirror. If we're removing a mirror that has some silent damage, we'll have exactly the same damage in the new location (assuming that the new location is also a mirror). 2. When we read from an indirect vdev that points to a mirror vdev, we only consider one copy of the data. This can lead to reduced effective redundancy, because we might read a bad copy of the data from one side of the mirror, and not retry the other, good side of the mirror. Note that the problem is not with the removal process, but rather after the removal has completed (having copied correct data to both sides of the mirror), if one side of the new mirror is silently damaged, we encounter the problem when reading the relocated data via the indirect vdev. Also note that the problem doesn't occur when ZFS knows that one side of the mirror is bad, e.g. when a disk entirely fails or is offlined. The impact is that reads (from indirect vdevs that point to mirrors) may return a checksum error even though the good data exists on one side of the mirror, and scrub doesn't repair all data on the mirror (if some of it is pointed to via an indirect vdev). The fix for this is complicated by "split blocks" - one logical block may be split into two (or more) pieces with each piece moved to a different new location. In this case we need to read all versions of each split (one from each side of the mirror), and figure out which combination of versions results in the correct checksum, and then repair the incorrect versions. This ensures that we supply the same redundancy whether you use device removal or not. For example, if a mirror has small silent errors on all of its children, we can still reconstruct the correct data, as long as those errors are at sufficiently-separated offsets (specifically, separated by the largest block size - default of 128KB, but up to 16MB). Porting notes: * A new indirect vdev check was moved from dsl_scan_needs_resilver_cb() to dsl_scan_needs_resilver(), which was added to ZoL as part of the sequential scrub work. * Passed NULL for zfs_ereport_post_checksum()'s zbookmark_phys_t parameter. The extra parameter is unique to ZoL. * When posting indirect checksum errors the ABD can be passed directly, zfs_ereport_post_checksum() is not yet ABD-aware in OpenZFS. Authored by: Matthew Ahrens <[email protected]> Reviewed by: Tim Chase <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Ported-by: Tim Chase <[email protected]> OpenZFS-issue: https://illumos.org/issues/9290 OpenZFS-commit: https://github.com/openzfs/openzfs/pull/591 Closes #6900
* OpenZFS 7614, 9064 - zfs device evacuation/removalMatthew Ahrens2018-04-141-0/+1925
OpenZFS 7614 - zfs device evacuation/removal OpenZFS 9064 - remove_mirror should wait for device removal to complete This project allows top-level vdevs to be removed from the storage pool with "zpool remove", reducing the total amount of storage in the pool. This operation copies all allocated regions of the device to be removed onto other devices, recording the mapping from old to new location. After the removal is complete, read and free operations to the removed (now "indirect") vdev must be remapped and performed at the new location on disk. The indirect mapping table is kept in memory whenever the pool is loaded, so there is minimal performance overhead when doing operations on the indirect vdev. The size of the in-memory mapping table will be reduced when its entries become "obsolete" because they are no longer used by any block pointers in the pool. An entry becomes obsolete when all the blocks that use it are freed. An entry can also become obsolete when all the snapshots that reference it are deleted, and the block pointers that reference it have been "remapped" in all filesystems/zvols (and clones). Whenever an indirect block is written, all the block pointers in it will be "remapped" to their new (concrete) locations if possible. This process can be accelerated by using the "zfs remap" command to proactively rewrite all indirect blocks that reference indirect (removed) vdevs. Note that when a device is removed, we do not verify the checksum of the data that is copied. This makes the process much faster, but if it were used on redundant vdevs (i.e. mirror or raidz vdevs), it would be possible to copy the wrong data, when we have the correct data on e.g. the other side of the mirror. At the moment, only mirrors and simple top-level vdevs can be removed and no removal is allowed if any of the top-level vdevs are raidz. Porting Notes: * Avoid zero-sized kmem_alloc() in vdev_compact_children(). The device evacuation code adds a dependency that vdev_compact_children() be able to properly empty the vdev_child array by setting it to NULL and zeroing vdev_children. Under Linux, kmem_alloc() and related functions return a sentinel pointer rather than NULL for zero-sized allocations. * Remove comment regarding "mpt" driver where zfs_remove_max_segment is initialized to SPA_MAXBLOCKSIZE. Change zfs_condense_indirect_commit_entry_delay_ticks to zfs_condense_indirect_commit_entry_delay_ms for consistency with most other tunables in which delays are specified in ms. * ZTS changes: Use set_tunable rather than mdb Use zpool sync as appropriate Use sync_pool instead of sync Kill jobs during test_removal_with_operation to allow unmount/export Don't add non-disk names such as "mirror" or "raidz" to $DISKS Use $TEST_BASE_DIR instead of /tmp Increase HZ from 100 to 1000 which is more common on Linux removal_multiple_indirection.ksh Reduce iterations in order to not time out on the code coverage builders. removal_resume_export: Functionally, the test case is correct but there exists a race where the kernel thread hasn't been fully started yet and is not visible. Wait for up to 1 second for the removal thread to be started before giving up on it. Also, increase the amount of data copied in order that the removal not finish before the export has a chance to fail. * MMP compatibility, the concept of concrete versus non-concrete devices has slightly changed the semantics of vdev_writeable(). Update mmp_random_leaf_impl() accordingly. * Updated dbuf_remap() to handle the org.zfsonlinux:large_dnode pool feature which is not supported by OpenZFS. * Added support for new vdev removal tracepoints. * Test cases removal_with_zdb and removal_condense_export have been intentionally disabled. When run manually they pass as intended, but when running in the automated test environment they produce unreliable results on the latest Fedora release. They may work better once the upstream pool import refectoring is merged into ZoL at which point they will be re-enabled. Authored by: Matthew Ahrens <[email protected]> Reviewed-by: Alex Reece <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: John Kennedy <[email protected]> Reviewed-by: Prakash Surya <[email protected]> Reviewed by: Richard Laager <[email protected]> Reviewed by: Tim Chase <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Approved by: Garrett D'Amore <[email protected]> Ported-by: Tim Chase <[email protected]> Signed-off-by: Tim Chase <[email protected]> OpenZFS-issue: https://www.illumos.org/issues/7614 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/f539f1eb Closes #6900
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