On Sat, Apr 23, 2016 at 08:03:33PM +0100, John wrote: > On 04/23/2016 07:22 PM, Graham Percival wrote: > > What I'm suggesting is this: > > > > filesystem RW -+--> (RW, run SQL, emails, etc) ---> filesystem RW > > |--> snapshot RO --> run tarsnap --> delete snapshot > > > > > > Essentially, you would not be making your *home directory* read-only. > > Instead, you could create a read-only copy of your home directory (which > > continues to be read-write), then you archive that *copy*. > > But the second, it seems to me, requires a partition (or filesystem, or > tree portion) to be copied to a large enough temporary space to hold the > full dataset which is to be archived, before the next update can be > accepted and the backup started side-by-side. If you think it can be > achieved without a full data copy being taken while the updates are > frozen then this will be a lightbulb-moment for me - continuing to > update while creating the copy is no different to updating while backing > up, it's just pushing the problem to one remove. I can see how it might > be achieved instantly with a mirror dataset, freezing one and continuing > to update the other, but we've not discussed those.
Does this help? http://www.tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html I've not tried it myself, but that's how I understand CoW filesystems work and it's as Graham described. Tim. -- Tim Bishop http://www.bishnet.net/tim/ PGP Key: 0x6C226B37FDF38D55
