ZFS Compression: Difference between revisions
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(Reworked a bit to be less 'notes about compression'. Updated some information.) |
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ZFS supports transparent compression of data at the block level for datasets. Enabling compression can improve storage efficiency by decreasing the amount of data written to disk and improve read performance for large files, as less data needs to be read from disk. | |||
If desired, compression will need to be enabled individually for all relevant OSTs. | |||
== Check ZFS compression == | == Check ZFS compression == | ||
<pre>zfs get compression < | <pre>zfs get compression <OST/dataset/here></pre> | ||
== Set ZFS compression == | == Set ZFS compression == | ||
<pre>zfs set compression=on < | <pre>zfs set compression=on <OST/dataset/here></pre> | ||
turns on compression with default algorithm ( | turns on compression with default algorithm (lz4 since ZFS version 0.6.5). You can chose values other than "on" for the compression algorithm, see 'man zfsprops' for details. | ||
To use a different algorithm, use for example "compression= | To use a different algorithm, use for example "compression=zstd" instead of "on". | ||
'''lz4''' is likely the best choice now. It has been tested extensively, and provides very good compression balanced with performance. | '''lz4''' is likely the best choice now. It has been tested extensively, and provides very good compression balanced with performance. It implements an early abort feature<ref>https://github.com/openzfs/zfs/blob/e0bf43d64ed01285321bf6c3a308f699c5483efc/module/zfs/lz4_zfs.c#L520</ref>, meaning it stops trying to compress if initial compression results do not meet a threshold, so performance with incompressible data isn't degraded. | ||
== Check compression ratio == | == Check compression ratio == | ||
On OSS: | On OSS: | ||
<pre>zfs get compressratio < | <pre>zfs get compressratio <OST/dataset/here></pre> | ||
On client machines: | On client machines: | ||
<pre>du --apparent-size -h <file/dir></pre> will show logical usage of a file (in human readable units), whereas <pre>du -h <file></pre> will show actual usage on disk (in human readable units). | |||
[[Category:ZFS]][[Category:Howto]] | |||
Latest revision as of 13:31, 15 October 2024
ZFS supports transparent compression of data at the block level for datasets. Enabling compression can improve storage efficiency by decreasing the amount of data written to disk and improve read performance for large files, as less data needs to be read from disk.
If desired, compression will need to be enabled individually for all relevant OSTs.
Check ZFS compression
zfs get compression <OST/dataset/here>
Set ZFS compression
zfs set compression=on <OST/dataset/here>
turns on compression with default algorithm (lz4 since ZFS version 0.6.5). You can chose values other than "on" for the compression algorithm, see 'man zfsprops' for details.
To use a different algorithm, use for example "compression=zstd" instead of "on".
lz4 is likely the best choice now. It has been tested extensively, and provides very good compression balanced with performance. It implements an early abort feature[1], meaning it stops trying to compress if initial compression results do not meet a threshold, so performance with incompressible data isn't degraded.
Check compression ratio
On OSS:
zfs get compressratio <OST/dataset/here>
On client machines:
du --apparent-size -h <file/dir>
will show logical usage of a file (in human readable units), whereas
du -h <file>
will show actual usage on disk (in human readable units).