Date: Wed, 26 Apr 2006 15:23:39 -0500 From: Eric Anderson <anderson@centtech.com> To: Kent Ho <kent@outblaze.com> Cc: freebsd-fs@freebsd.org Subject: Re: Do I need to reserve disk space for UFS snapshots? Message-ID: <444FD6CB.2080805@centtech.com> In-Reply-To: <444FA4CF.7040507@outblaze.com> References: <444FA4CF.7040507@outblaze.com>
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Kent Ho wrote: > Hi, > > I'm planing to use FreeBSD snapshots. It seems to be the snapshop image > is placed on the same file system. The question is how do I manage or > reserve space for the snapshots? Can someone give me some guidelines or > pointers. > > Here's my netapp it has a separate area allocated for the snapshots, I'm > keeping 2 weekly snapshots in there(weekly.0 & weekly.1) using around 30G. > > Filesystem kbytes used avail capacity Mounted on > /vol/vol0/ 305052552 272495320 32557232 89% /vol/vol0/ > /vol/vol0/.snapshot 76263136 30658028 45605108 40% > /vol/vol0/.snapshot > > Filesystem iused ifree %iused Mounted on > /vol/vol0/ 10802387 89822586 11% /vol/vol0/ > > If copy all content in vol0 to a FreeBSD and make 2 snapshot will it be > around the same? 272G + 30G = 302G? So if I df on the FreeBSD box > around 302G will be used? > > Any help and information is highly appreciated. FreeBSD snapshots do not work the same way as NetApp snapshots. First, they must reside on the same filesystem as the snapshotted filesystem. They will initially eat up some space upon creation equal to the space used by the cylinder group summaries and superblocks, but it isn't a whole lot. You'll need to have however much space is changed weekly for each snapshot, so if 10Gb per week is changed, then you'll need that much space per snapshot file done. Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
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