From 379ca9cf2beba802f096273e89e30914a2d6bafc Mon Sep 17 00:00:00 2001 From: Olaf Faaland Date: Fri, 7 Jul 2017 20:20:35 -0700 Subject: Multi-modifier protection (MMP) Add multihost=on|off pool property to control MMP. When enabled a new thread writes uberblocks to the last slot in each label, at a set frequency, to indicate to other hosts the pool is actively imported. These uberblocks are the last synced uberblock with an updated timestamp. Property defaults to off. During tryimport, find the "best" uberblock (newest txg and timestamp) repeatedly, checking for change in the found uberblock. Include the results of the activity test in the config returned by tryimport. These results are reported to user in "zpool import". Allow the user to control the period between MMP writes, and the duration of the activity test on import, via a new module parameter zfs_multihost_interval. The period is specified in milliseconds. The activity test duration is calculated from this value, and from the mmp_delay in the "best" uberblock found initially. Add a kstat interface to export statistics about Multiple Modifier Protection (MMP) updates. Include the last synced txg number, the timestamp, the delay since the last MMP update, the VDEV GUID, the VDEV label that received the last MMP update, and the VDEV path. Abbreviated output below. $ cat /proc/spl/kstat/zfs/mypool/multihost 31 0 0x01 10 880 105092382393521 105144180101111 txg timestamp mmp_delay vdev_guid vdev_label vdev_path 20468 261337 250274925 68396651780 3 /dev/sda 20468 261339 252023374 6267402363293 1 /dev/sdc 20468 261340 252000858 6698080955233 1 /dev/sdx 20468 261341 251980635 783892869810 2 /dev/sdy 20468 261342 253385953 8923255792467 3 /dev/sdd 20468 261344 253336622 042125143176 0 /dev/sdab 20468 261345 253310522 1200778101278 2 /dev/sde 20468 261346 253286429 0950576198362 2 /dev/sdt 20468 261347 253261545 96209817917 3 /dev/sds 20468 261349 253238188 8555725937673 3 /dev/sdb Add a new tunable zfs_multihost_history to specify the number of MMP updates to store history for. By default it is set to zero meaning that no MMP statistics are stored. When using ztest to generate activity, for automated tests of the MMP function, some test functions interfere with the test. For example, the pool is exported to run zdb and then imported again. Add a new ztest function, "-M", to alter ztest behavior to prevent this. Add new tests to verify the new functionality. Tests provided by Giuseppe Di Natale. Reviewed by: Matthew Ahrens Reviewed-by: Giuseppe Di Natale Reviewed-by: Ned Bass Reviewed-by: Andreas Dilger Reviewed-by: Brian Behlendorf Signed-off-by: Olaf Faaland Closes #745 Closes #6279 --- man/man8/zpool.8 | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'man/man8/zpool.8') diff --git a/man/man8/zpool.8 b/man/man8/zpool.8 index ea25da300..69d77e961 100644 --- a/man/man8/zpool.8 +++ b/man/man8/zpool.8 @@ -717,6 +717,25 @@ The default value is .Sy off . This property can also be referred to by its shortened name, .Sy listsnaps . +.It Sy multihost Ns = Ns Sy on Ns | Ns Sy off +Controls whether a pool activity check should be performed during +.Nm zpool Cm import . +When a pool is determined to be active it cannot be imported, even with the +.Fl f +option. This property is intended to be used in failover configurations +where multiple hosts have access to a pool on shared storage. When this +property is on, periodic writes to storage occur to show the pool is in use. +See +.Sy zfs_multihost_interval +in the +.Xr zfs-module-parameters 5 +man page. In order to enable this property each host must set a unique hostid. +See +.Xr genhostid 1 +and +.Xr spl-module-paramters 5 +for additional details. The default value is +.Sy off . .It Sy version Ns = Ns Ar version The current on-disk version of the pool. This can be increased, but never decreased. @@ -2335,7 +2354,7 @@ is not set, it is assumed that the user is allowed to run .Sh INTERFACE STABILITY .Sy Evolving .Sh SEE ALSO -.Xr zed 8 +.Xr zed 8 , .Xr zfs 8 , .Xr zfs-events 5 , .Xr zfs-module-parameters 5 , -- cgit v1.2.3