[linux-lvm] What have snapshots got to do with LVM ?
Heinz J. Mauelshagen
Mauelshagen at sistina.com
Mon Apr 23 12:05:21 UTC 2001
On Mon, Apr 23, 2001 at 09:38:18AM +0100, Joe Thornber wrote:
> On Mon, Apr 23, 2001 at 10:21:45AM +0000, Heinz J. Mauelshagen wrote:
> > On Sun, Apr 22, 2001 at 01:09:24PM +0100, Joe Thornber wrote:
> > > Just a random Sunday morning thought:
> > >
> > > Why don't we split snapshots off into their own driver so we can
> > > snapshot any block device, putting the COW tables on any other block
> > > device ?
> >
> > Any other block device devides into PE similar allocation units carrying their
> > own COW exception table at the beginning?
>
> I'm not sure I understand your comment. There are two devices the
> snapshot origin and the snapshot storage device. We can divide the
> snapshot storage device up how we want, the COW exception tables go in
> here.
With LVM sanpshots we devide a device into PEs, allocate parts of the
COW table dealing with exceptions stored in a specific PE at the very
beginning of the PE.
My point is, that a similar allocation policy needs to take place on a
general block device too in order to avoid disk access overhead.
>
> - Joe
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--
Regards,
Heinz -- The LVM Guy --
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Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
Mauelshagen at Sistina.com +49 2626 141200
FAX 924446
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