Date: Sun, 21 Sep 2014 10:00:40 -0700 From: Peter Wemm <peter@wemm.org> To: freebsd-current@freebsd.org Cc: Allan Jude <allanjude@freebsd.org> Subject: Re: zpool frag Message-ID: <1691600.4gjp5IhhyR@overcee.wemm.org> In-Reply-To: <541EE962.2000801@freebsd.org> References: <1411289830171-5950788.post@n5.nabble.com> <541EE962.2000801@freebsd.org>
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--nextPart2139920.ZNsoPLKslq Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" On Sunday, September 21, 2014 11:06:10 AM Allan Jude wrote: > On 2014-09-21 04:57, Beeblebrox wrote: > > FRAG means fragmentation, right? Zpool fragmentation? That's news t= o me. > > If > > this is real how do I fix it? > >=20 > > NAME SIZE ALLOC FREE FRAG EXPANDSZ CAP DEDUP HEALTH= =20 > > ALTROOT pool1 75.5G 53.7G 21.8G 60% - 71% 1.0= 0x=20 > > ONLINE - pool2 48.8G 26.2G 22.6G 68% - 53% 1= .00x=20 > > ONLINE - pool3 204G 177G 27.0G 53% - 86% 1= .11x=20 > > ONLINE - > >=20 > > Regards. > >=20 > >=20 > >=20 > > ----- > > 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@freeb= sd.org" >=20 > 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 wil= l > have more random seek time while reading from the pool. >=20 > 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. >=20 > It is a fairly natural side effect of a copy-on-write file system. >=20 > Note: the % is not the % fragmented, IIRC, it is the percentage of th= e > free blocks that are less that a specific size. I forget what that si= ze is. I fear that the information presented in its current form is going to g= enerate=20 lots of fear and confusion. The other thing to consider is that this gets much, much worse as the p= ool=20 fills up. Even UFS has issues with fragmentation when it fills, but ZF= S is far=20 more sensative to it. In the freebsd.org cluster we have a health chec= k alert=20 at 80% full, but even that's probably on the high side. =2D-=20 Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI= 6FJV UTF-8: for when a ' or ... just won\342\200\231t do\342\200\246 --nextPart2139920.ZNsoPLKslq Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABAgAGBQJUHwQ+AAoJEDXWlwnsgJ4E9VMH/iTx9u9RTWOEbAiDJrZ8M23p ZediIzo2ZZjea9+NL9kGF/oiV0a+wyAOCL84unX+KxWBAipL8d6/7R4cP4y67fYn aICNy9BkHVWLYm09UN1TYjSzI6qshagrCG0CWbWunPx6EmkBhFD0xhQNazUKweQf zpAv62Lul35dUKy11jMb2y4WcjQhcZDGFUyJ0unTvg9l9tyddxsdTvoBCQuNvTP1 B+UAFHKQhHnnoKLCUSDosgjvnIuOsJP0Iv+C/e6LdLB1SJd3V6c+yoCdi3mdf+T9 SiPmvDBXIJmGrAVwzGjSEK1xw9J2RXFLVI0bN2edmO0kLHC4ZGAhbiYggPIzZJA= =JBr4 -----END PGP SIGNATURE----- --nextPart2139920.ZNsoPLKslq--
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