On Fri, March 19, 2010 12:25, Darren J Moffat wrote: > On 19/03/2010 17:19, David Dyer-Bennet wrote: >> >> On Fri, March 19, 2010 11:33, Darren J Moffat wrote: >>> On 19/03/2010 16:11, joerg.schill...@fokus.fraunhofer.de wrote: >>>> Darren J Moffat<darr...@opensolaris.org> wrote: >>>> >>>>> I'm curious, why isn't a 'zfs send' stream that is stored on a tape >>>>> yet >>>>> the implication is that a tar archive stored on a tape is considered >>>>> a >>>>> backup ? >>>> >>>> You cannot get a single file out of the zfs send datastream. >>> >>> I don't see that as part of the definition of a backup - you obviously >>> do - so we will just have to disagree on that. >> >> I used to. Now I think more in terms of getting it from a snapshot >> maintained online on the original storage server. > > Exactly! The single file retrieval due to user error case is best > achieved by an automated snapshot system. ZFS+CIFS even provides > Windows Volume Shadow Services so that Windows users can do this on > their own.
I'll need to look into that, when I get a moment. Not familiar with Windows Volume Shadow Services, but having people at home able to do this directly seems useful. >> The overall storage strategy has to include retrieving files lost due to >> user error over some time period, whether that's months or years. And >> having to restore an entire 100TB backup to "spare disk" somewhere to >> get >> one file is clearly not on. > > Completely agree, no where was I suggesting that 'zfs send' out to tape > should be the whole backup strategy. I even pointed to a presentation > given at LOSUG that shows how someone is doing this. Sorry, didn't mean to sound like I was arguing with you (or suggest we disagreed in that area); I intended to pontificate on the problem in general. > I'll say it again: neither 'zfs send' or (s)tar is an enterprise (or > even home) backup system on their own one or both can be components of > the full solution. I'm seeing what a lot of professional and serious amateur photographers are building themselves for storage on a mailing list I'm on. Nearly always it consists of two layers of storage servers, often with one off-site (most of them keep current photos on LOCAL disk, instead of my choice of working directly off storage server disk). I'm in the fortunate position of having my backups less than the size of a large single drive; so I'm rotating three backup drives, and intend to be taking one of them off-site regularly (still in the process of converting to this new scheme; the previous scheme used off-site optical disks). I use ZFS for the removable drives, so I can if necessary reach into them and drag out single files fairly easily if necessary (but "necessary" would require something happening to the online snapshot first). People with much bigger configurations look like they save money using tape for the archival / disaster restore storage, but it's not economically viable at my level. -- David Dyer-Bennet, d...@dd-b.net; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
