Review the following sections if you are unsure how ZFS reports file system and pool space accounting. Also review ZFS Disk Space Accounting.
The zpool list and zfs list commands are better than the previous df and du commands for determining your available pool and file system space. With the legacy commands, you cannot easily discern between pool and file system space, nor do the legacy commands account for space that is consumed by descendent file systems or snapshots.
For example, the following root pool (rpool) has 5.46 GB allocated and 68.5 GB free.
# zpool list rpool NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 74G 5.46G 68.5G 7% 1.00x ONLINE -
If you compare the pool space accounting with the file system space accounting by reviewing the USED column of your individual file systems, you can see that the pool space that is reported in ALLOC is accounted for in the file systems' USED total. For example:
# zfs list -r rpool NAME USED AVAIL REFER MOUNTPOINT rpool 5.41G 67.4G 74.5K /rpool rpool/ROOT 3.37G 67.4G 31K legacy rpool/ROOT/solaris 3.37G 67.4G 3.07G / rpool/ROOT/solaris/var 302M 67.4G 214M /var rpool/dump 1.01G 67.5G 1000M - rpool/export 97.5K 67.4G 32K /rpool/export rpool/export/home 65.5K 67.4G 32K /rpool/export/home rpool/export/home/admin 33.5K 67.4G 33.5K /rpool/export/home/admin rpool/swap 1.03G 67.5G 1.00G -
The SIZE value that is reported by the zpool list command is generally the amount of physical disk space in the pool, but varies depending on the pool's redundancy level. See the examples below. The zfs list command lists the usable space that is available to file systems, which is disk space minus ZFS pool redundancy metadata overhead, if any.
The following ZFS dataset configurations are tracked as allocated space by the zfs list command but they are not tracked as allocated space in the zpool list output:
ZFS file system quota
ZFS file system reservation
ZFS logical volume size
The following items describes how different pool configurations impact zpool list and zfs list output:
Non-redundant storage pool – When a pool is created with one 136-GB disk, the zpool list command reports SIZE and initial FREE values as 136 GB. The initial AVAIL space reported by the zfs list command is 134 GB, due to a small amount of pool metadata overhead. For example:
# zpool create tank c0t6d0 # zpool list tank NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT tank 136G 95.5K 136G 0% 1.00x ONLINE - # zfs list tank NAME USED AVAIL REFER MOUNTPOINT tank 72K 134G 21K /tank
Mirrored storage pool – When a pool is created with two 136-GB disks, zpool list command reports SIZE as 136 GB and initial FREE value as 136 GB. This reporting is referred to as the deflated space value. The initial AVAIL space reported by the zfs list command is 134 GB, due to a small amount of pool metadata overhead. For example:
# zpool create tank mirror c0t6d0 c0t7d0 # zpool list tank NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT tank 136G 95.5K 136G 0% 1.00x ONLINE - # zfs list tank NAME USED AVAIL REFER MOUNTPOINT tank 72K 134G 21K /tank
RAID-Z storage pool – When a raidz2 pool is created with three 136-GB disks, the zpool list commands reports SIZE as 408 GB and initial FREE value as 408 GB. This reporting is referred to as the inflated disk space value, which includes redundancy overhead, such as parity information. The initial AVAIL space reported by the zfs list command is 133 GB, due to the pool redundancy overhead. The space discrepancy between the zpool list and the zfs list output for a RAID-Z pool is because zpool list reports the inflated pool space.
# zpool create tank raidz2 c0t6d0 c0t7d0 c0t8d0 # zpool list tank NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT tank 408G 286K 408G 0% 1.00x ONLINE - # zfs list tank NAME USED AVAIL REFER MOUNTPOINT tank 73.2K 133G 20.9K /tank
For information about how recordsize changes can impact RAIDZ space accounting, see ZFS Disk Space Accounting.
NFS mounted file system space – Neither the zpool list or the zfs list account for NFS mounted file system space. However, local data files can be hidden under a mounted NFS file system. If you are missing file system space, ensure that you do not have data files hidden under an NFS file system.