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?
> 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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