25.7 ZFS 压缩

查看各个 ZFS 文件系统的数据压缩属性及其当前设置：

# zfs get compression
NAME                PROPERTY     VALUE           SOURCE
zroot               compression  lz4             local
zroot/ROOT          compression  lz4             inherited from zroot
zroot/ROOT/default  compression  lz4             inherited from zroot
zroot/home          compression  lz4             inherited from zroot
zroot/home/ykla     compression  lz4             inherited from zroot
zroot/tmp           compression  lz4             inherited from zroot
zroot/usr           compression  lz4             inherited from zroot
zroot/usr/ports     compression  lz4             inherited from zroot
zroot/usr/src       compression  lz4             inherited from zroot
zroot/var           compression  lz4             inherited from zroot
zroot/var/audit     compression  lz4             inherited from zroot
zroot/var/crash     compression  lz4             inherited from zroot
zroot/var/log       compression  lz4             inherited from zroot
zroot/var/mail      compression  lz4             inherited from zroot
zroot/var/tmp       compression  lz4             inherited from zroot

将 zroot 文件系统的数据压缩算法设置为 zstd-5 级别：

# zfs set compression=zstd-5 zroot

系统重启后，再次列出各个 ZFS 文件系统的数据压缩属性及其当前设置：

# zfs get compression
NAME                PROPERTY     VALUE           SOURCE
zroot               compression  zstd-5          local
zroot/ROOT          compression  zstd-5          inherited from zroot
zroot/ROOT/default  compression  zstd-5          inherited from zroot
zroot/home          compression  zstd-5          inherited from zroot
zroot/home/ykla     compression  zstd-5          inherited from zroot
zroot/tmp           compression  zstd-5          inherited from zroot
zroot/usr           compression  zstd-5          inherited from zroot
zroot/usr/ports     compression  zstd-5          inherited from zroot
zroot/usr/src       compression  zstd-5          inherited from zroot
zroot/var           compression  zstd-5          inherited from zroot
zroot/var/audit     compression  zstd-5          inherited from zroot
zroot/var/crash     compression  zstd-5          inherited from zroot
zroot/var/log       compression  zstd-5          inherited from zroot
zroot/var/mail      compression  zstd-5          inherited from zroot
zroot/var/tmp       compression  zstd-5          inherited from zroot

查看各个 ZFS 文件系统的实际数据压缩比：

# zfs get compressratio
NAME                PROPERTY       VALUE  SOURCE
zroot               compressratio  2.70x  -
zroot/ROOT          compressratio  2.68x  -
zroot/ROOT/default  compressratio  2.68x  -
zroot/home          compressratio  1.00x  -
zroot/home/ykla     compressratio  1.01x  -
zroot/tmp           compressratio  1.00x  -
zroot/usr           compressratio  2.73x  -
zroot/usr/ports     compressratio  1.00x  -
zroot/usr/src       compressratio  2.73x  -
zroot/var           compressratio  1.47x  -
zroot/var/audit     compressratio  1.00x  -
zroot/var/crash     compressratio  1.01x  -
zroot/var/log       compressratio  2.90x  -
zroot/var/mail      compressratio  1.00x  -
zroot/var/tmp       compressratio  1.00x  -