From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 9 Jun 2000 08:59:45 +0200 From: "Heinz J. Mauelshagen" Subject: Re: [linux-lvm] LVM 0.8final for 2.2.15/2.2.16? Message-ID: <20000609085945.C6522@hmsysv.t-online.de> Reply-To: Mauelshagen@Sistina.com References: <20000608103415.A3935@gruyere.muc.suse.de> <20000608143407.D9694@jadzia.josv.com> Mime-Version: 1.0 In-Reply-To: <20000608143407.D9694@jadzia.josv.com>; from josv@osp.nl on Thu, Jun 08, 2000 at 02:34:07PM +0200 Sender: owner-linux-lvm Errors-To: owner-linux-lvm List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jos Visser Cc: linux-lvm@msede.com 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. Exactly. That's why i'll implement atomic activation off multiple snapshot. The idea is: - prepare multiple _inactive_ snapshots - activate them afterwards at once Heinz > 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). > > ++Jos > > -- > The InSANE quiz master is always right! > (or was it the other way round? :-) -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Sistina Software Inc. Senior Consultant/Developer Bartningstr. 12 64289 Darmstadt Germany Mauelshgen@Sistina.com +49 6151 710386 FAX 710396 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-