zpool frag
Allan Jude
allanjude at freebsd.org
Sun Sep 21 15:06:19 UTC 2014
On 2014-09-21 04:57, Beeblebrox wrote:
> FRAG means fragmentation, right? Zpool fragmentation? That's news to me. If
> this is real how do I fix it?
>
> NAME SIZE ALLOC FREE FRAG EXPANDSZ CAP DEDUP HEALTH ALTROOT
> pool1 75.5G 53.7G 21.8G 60% - 71% 1.00x ONLINE -
> pool2 48.8G 26.2G 22.6G 68% - 53% 1.00x ONLINE -
> pool3 204G 177G 27.0G 53% - 86% 1.11x ONLINE -
>
> Regards.
>
>
>
> -----
> FreeBSD-11-current_amd64_root-on-zfs_RadeonKMS
> --
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It is not something you 'fix', it is just a metric to help you
understand the performance of your pool. The higher the fragmentation,
the longer it might take to allocate new space, and obviously you will
have more random seek time while reading from the pool.
As Steven mentions, there is no defragmentation tool for ZFS. You can
zfs send/recv or backup/restore the pool if you have a strong enough
reason to want to get the fragmentation number down.
It is a fairly natural side effect of a copy-on-write file system.
Note: the % is not the % fragmented, IIRC, it is the percentage of the
free blocks that are less that a specific size. I forget what that size is.
--
Allan Jude
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