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authorMatthew Ahrens <[email protected]>2013-03-24 13:24:51 -0800
committerBrian Behlendorf <[email protected]>2014-07-16 11:52:46 -0700
commitd5869641416362c82bb7f090d13af4b86a7270f9 (patch)
treeb133416338fd72a5990e34fbfc97fab3adc60ee8 /META
parent61e99a73bc34d602639c5a991abdc1e011a52d8d (diff)
Illumos #3641 compressed block histograms with zdb
This patch is a zdb extension of the '-b' option, producing a histogram of the physical compressed block sizes per DMU object type on disk. The '-bbbb' option to zdb will uncover this new feature; here's an example usage on a new pool and snippet of the output it generates: # zpool create tank /dev/vd{b,c,d} # dd bs=1k if=/dev/urandom of=/tank/1kfile count=1 # dd bs=3k if=/dev/urandom of=/tank/3kfile count=1 # dd bs=64k if=/dev/urandom of=/tank/64kfile count=1 # zdb -bbbb tank ... 3 68.0K 68.0K 68.0K 22.7K 1.00 34.26 ZFS plain file psize (in 512-byte sectors): number of blocks 2: 1 * 3: 0 4: 0 5: 0 6: 1 * 7: 0 ... 127: 0 128: 1 * ... The blocks are also broken down by their indirection level. Expanding on the above example: # zfs set recordsize=1k tank # dd bs=1k if=/dev/urandom of=/tank/2x1kfile count=2 # zdb -bbbb tank ... 1 16K 1K 2K 2K 16.00 1.02 L1 ZFS plain file psize (in 512-byte sectors): number of blocks 2: 1 * 5 70.0K 70.0K 70.0K 14.0K 1.00 35.71 L0 ZFS plain file psize (in 512-byte sectors): number of blocks 2: 3 *** 3: 0 4: 0 5: 0 6: 1 * 7: 0 ... 127: 0 128: 1 * 6 86.0K 71.0K 72.0K 12.0K 1.21 36.73 ZFS plain file psize (in 512-byte sectors): number of blocks 2: 4 **** 3: 0 4: 0 5: 0 6: 1 * 7: 0 ... 127: 0 128: 1 * ... There's now a single 1K L1 block which is the indirect block needed for the '2x1kfile' file just created, as well as two more 1K L0 blocks from the same file. This can be used to get a distribution of the block sizes used within the pool, on a per object type basis. References: https://illumos.org/issues/3641 https://github.com/illumos/illumos-gate/commit/490d05b Ported by: Tim Chase <[email protected]> Signed-off-by: Prakash Surya <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Boris Protopopov <[email protected]> Closes #2456
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