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| zfstuningguide [2018/12/19 12:53] – link to a new website serving ZFS Evil Tuning Guide; the old one is down MateuszPiotrowski | zfstuningguide [2023/04/02 17:15] (current) – 2 GB minimum for ZFS, according to OpenZFS documentation. GrahamPerrin | ||
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| See also: [[https:// | See also: [[https:// | ||
| ===== ZFS Tuning Guide ===== | ===== ZFS Tuning Guide ===== | ||
| - | (Work in Progress) | ||
| - | To use ZFS, at least 1& | + | [[https:// |
| + | |||
| + | Depending on your workload, it may be possible to use ZFS on systems with less memory, but it requires careful tuning to avoid panics from memory exhaustion in the kernel. | ||
| A 64-bit system is preferred due to its larger address space and better performance on 64-bit variables, which are used extensively by ZFS. 32-bit systems are supported though, with sufficient tuning. | A 64-bit system is preferred due to its larger address space and better performance on 64-bit variables, which are used extensively by ZFS. 32-bit systems are supported though, with sufficient tuning. | ||
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| ==== Application Issues ==== | ==== Application Issues ==== | ||
| - | ZFS is a copy-on-write filesystem. As such metadata from the top of the hierarchy is copied in order to maintain consistency in case of sudden failure, i.e. loss of power during a write operation. This obviates the need for an fsck-like requirement of ZFS filesystems at boot. However the downside to this is that applications which perform updates in place to large files, e.g. databases, will likely perform poorly in this application of the filesystem due to excessive I/O from copy-on-write (a fast SLOG device -- e.g. a SSD -- can help regarding the write performance of databases or any application which is doing synchronous writes (e.g. open with O_FSYNC) to the FS to make sure the data is on non-volatile storage when the write-call returns). Additionally, | + | ZFS is a copy-on-write filesystem. As such metadata from the top of the hierarchy is copied in order to maintain consistency in case of sudden failure, i.e. loss of power during a write operation. This obviates the need for an fsck-like requirement of ZFS filesystems at boot. However the downside to this is that applications which perform updates in place to large files, e.g. databases, will likely perform poorly in this application of the filesystem due to excessive I/O from copy-on-write (a fast SLOG device -- e.g. a SSD -- can help regarding the write performance of databases or any application which is doing synchronous writes (e.g. open with O_FSYNC) to the FS to make sure the data is on non-volatile storage when the write-call returns). Additionally, |
| ===== General Tuning ===== | ===== General Tuning ===== | ||
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| # Set TXG write limit to a lower threshold. | # Set TXG write limit to a lower threshold. | ||
| # the throughput rate (see "zpool iostat" | # the throughput rate (see "zpool iostat" | ||
| - | # for systems with 4 GB of RAM, while 1 GB works well for us w/ 8 GB on | + | # for systems with 4 GB of RAM, while 1 GB works well for us w/ 8 GB on |
| # disks which have 64 MB cache. << | # disks which have 64 MB cache. << | ||
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| < | < | ||
| - | vfs.zfs.zil_disable=" | + | vfs.zfs.zil_disable=" |
| </ | </ | ||
| the vfs.zfs.zil_disable loader tunable was replaced with the " | the vfs.zfs.zil_disable loader tunable was replaced with the " | ||
| - | Disabling ZIL is not recommended where data consistency is required (such as database servers) but will not result in file system corruption. See http://www.solarisinternals.com/wiki/ | + | Disabling ZIL is not recommended where data consistency is required (such as database servers) but will not result in file system corruption. See [[https://archive.is/pV9cy|ZFS Evil Tuning Guide]], section " |
| ZFS is designed to be used with " | ZFS is designed to be used with " | ||
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| References | References | ||
| - | *[[https:// | + | *[[https:// |
| ===== Scrub and Resilver Performance ===== | ===== Scrub and Resilver Performance ===== | ||
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| ---- | ---- | ||
| - | {{tag>Zfs HowTo}} | + | {{tag> |
| + | {{tag> | ||
| + | {{tag> | ||
| + | {{tag> | ||