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| -rw-r--r-- | man/man8/zpool.8 | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/man/man8/zpool.8 b/man/man8/zpool.8 index 7ba8a5bae..f52f9ee39 100644 --- a/man/man8/zpool.8 +++ b/man/man8/zpool.8 @@ -587,6 +587,11 @@ The following are read-only properties: .Bl -tag -width Ds .It Cm allocated Amount of storage used within the pool. +See +.Sy fragmentation +and +.Sy free +for more information. .It Sy capacity Percentage of pool space used. This property can also be referred to by its shortened column name, @@ -601,9 +606,28 @@ been brought online .Pc . This space occurs when a LUN is dynamically expanded. .It Sy fragmentation -The amount of fragmentation in the pool. +The amount of fragmentation in the pool. As the amount of space +.Sy allocated +increases, it becomes more difficult to locate +.Sy free +space. This may result in lower write performance compared to pools with more +unfragmented free space. .It Sy free The amount of free space available in the pool. +By contrast, the +.Xr zfs 8 +.Sy available +property describes how much new data can be written to ZFS filesystems/volumes. +The zpool +.Sy free +property is not generally useful for this purpose, and can be substantially more than the zfs +.Sy available +space. This discrepancy is due to several factors, including raidz party; zfs +reservation, quota, refreservation, and refquota properties; and space set aside by +.Sy spa_slop_shift +(see +.Xr zfs-module-parameters 5 +for more information). .It Sy freeing After a file system or snapshot is destroyed, the space it was using is returned to the pool asynchronously. |