Difference between revisions of "Performance tuning"

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Performance tuning (view source)

Revision as of 21:32, 27 June 2020

8 bytes added ,  21:32, 27 June 2020
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Fixed github url
m (Added more information on incompressible data under LZ4 compression)
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-o ashift= is convenient, but it is flawed in that the creation of pools containing top level vdevs that have multiple optimal sector sizes require the use of multiple commands. [http://www.listbox.com/member/archive/182191/2013/07/search/YXNoaWZ0/sort/time_rev/page/2/entry/16:58/20130709002459:82E21654-E84F-11E2-A0FF-F6B47351D2F5/ A newer syntax] that will rely on the actual sector sizes has been discussed as a cross platform replacement and will likely be implemented in the future.
-o ashift= is convenient, but it is flawed in that the creation of pools containing top level vdevs that have multiple optimal sector sizes require the use of multiple commands. [http://www.listbox.com/member/archive/182191/2013/07/search/YXNoaWZ0/sort/time_rev/page/2/entry/16:58/20130709002459:82E21654-E84F-11E2-A0FF-F6B47351D2F5/ A newer syntax] that will rely on the actual sector sizes has been discussed as a cross platform replacement and will likely be implemented in the future.


In addition, [[User:Ryao | Richard Yao]] has contributed a [https://github.com/zfsonlinux/zfs/blob/master/cmd/zpool/zpool_vdev.c#L108 database of drives known to misreport sector sizes] to the ZFS on Linux project. It is used to automatically adjust ashift without the assistance of the system administrator. This approach is unable to fully compensate for misreported sector sizes whenever drive identifiers are used ambiguously (e.g. virtual machines, iSCSI LUNs, some rare SSDs), but it does a great amount of good. The format is roughly compatible with illumos' sd.conf and it is expected that other implementations will integrate the database in future releases. Strictly speaking, this database does not belong in ZFS, but the difficulty of patching the Linux kernel (especially older ones) necessitated that this be implemented in ZFS itself for Linux. The same is true for MacZFS. However, FreeBSD and illumos are both able to implement this in the correct layer.
In addition, [[User:Ryao | Richard Yao]] has contributed a [https://github.com/openzfs/zfs/blob/master/cmd/zpool/os/linux/zpool_vdev_os.c#L98 database of drives known to misreport sector sizes] to the ZFS on Linux project. It is used to automatically adjust ashift without the assistance of the system administrator. This approach is unable to fully compensate for misreported sector sizes whenever drive identifiers are used ambiguously (e.g. virtual machines, iSCSI LUNs, some rare SSDs), but it does a great amount of good. The format is roughly compatible with illumos' sd.conf and it is expected that other implementations will integrate the database in future releases. Strictly speaking, this database does not belong in ZFS, but the difficulty of patching the Linux kernel (especially older ones) necessitated that this be implemented in ZFS itself for Linux. The same is true for MacZFS. However, FreeBSD and illumos are both able to implement this in the correct layer.


=== Compression ===
=== Compression ===
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