====== ZFS compresison ======

<code bash>
zfs get compression
zfs get compression /rpool

zfs get compressratio 
zfs get compressratio /rpool

zfs get compression,compressratio,used,logicalused,referenced,logicalreferenced rpool/data/subvol-118-disk-0
</code>


===== switch to ZSTD =====

From OpenZFS 2.0.0 there is support for ZSTD:

<code bash>
zpool get all | grep compr
nvmpool  feature@lz4_compress           active                         local
nvmpool  feature@zstd_compress          disabled                       local
rpool    feature@lz4_compress           active                         local
rpool    feature@zstd_compress          disabled                       local

zfs get all rpool | grep compr
rpool  compressratio         1.16x                   -
rpool  compression           on                      local
rpool  refcompressratio      1.00x                   -
</code>

<code bash>
zfs set compression=zstd rpool/data
cannot set property for 'rpool/data': pool and or dataset must be upgraded to set this property or value
</code>

OpenZFS ZSTD compression level is 3 (available range is 1-19). To change it to 9:
<code bash>
zfs set compression=zstd-9 rpool/data
</code>
NOTE: it significantly increase CPU usage when writing huge amount of data (RAW movies). The best results for RAW movies is ''off'' or ''lz4''.