[linux-lvm] LVM 0.8final for 2.2.15/2.2.16?
Heinz J. Mauelshagen
Mauelshagen at Sistina.com
Fri Jun 9 06:59:45 UTC 2000
On Thu, Jun 08, 2000 at 02:34:07PM +0200, Jos Visser wrote:
> And thus it came to pass that Paul Jakma wrote:
> (on Thu, Jun 08, 2000 at 12:49:53PM +0100 to be exact)
> > On Thu, 8 Jun 2000, Andi Kleen wrote:
> > > consider a database that uses user space journaling using fsync:
> > > to make its disk files consistent after the snapshot it requires
> > > both the log write and the data write. When one is missing the
> > > log needs to be replayed, which requires writes.
> > but doesn't the call to block_fsync that Heinz confirmed exists cover
> > this?
> > nothing can cover the case where app data consistency depends on a future
> > write(). But that's the app's problem, and anyway a good database should
> > be consistent/recover itself if it's died between write(?)'s. right?
> > (in which case lvm snapshot is perfectly suitable for backing up
> > databases..)
> Most databases want you to store their log and data spaces in different
> (logical) volumes.
That's why i'll implement atomic activation off multiple snapshot.
The idea is:
- prepare multiple _inactive_ snapshots
- activate them afterwards at once
> To create a consistent image you would want to be
> able to snapshot multiple logical volumes atomically in one operation.
> HP's LVM supports this through the "multiple atomical lvsplit"
> feature (as of HP-UX 10 if memory serves me right).
> The InSANE quiz master is always right!
> (or was it the other way round? :-)
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Bartningstr. 12
Mauelshgen at Sistina.com +49 6151 710386
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