Date: Wed, 1 Oct 2014 11:09:32 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Allan Jude <allanjude@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: zpool frag Message-ID: <20141001180932.GA43300@funkthat.com> In-Reply-To: <541EE962.2000801@freebsd.org> References: <1411289830171-5950788.post@n5.nabble.com> <541EE962.2000801@freebsd.org>
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Allan Jude wrote this message on Sun, Sep 21, 2014 at 11:06 -0400: > 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 > > -- > > View this message in context: http://freebsd.1045724.n5.nabble.com/zpool-frag-tp5950788.html > > Sent from the freebsd-current mailing list archive at Nabble.com. > > _______________________________________________ > > freebsd-current@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-current > > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" > > > > 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. Can we get this documented in the zpool man page? I assume that the FRAG is the same as: fragmentation The amount of fragmentation in the pool. and that description is woefully lacking.. -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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