On Wed, Oct 14, 2009 at 10:36:01AM -0700, James A. Peltier wrote: > On Tue, 13 Oct 2009, Pasi Kärkkäinen wrote: > > > > >Hmm.. what kind of problems do you have with snapshots? > > Let's see > > They take up 16MB of space regardless of the amount of data that changes. > A single bit changes and 16MB is taken up. This is not tunable. > EQL volumes are based on 'pages', that are (afaik) 16 MB in size. So the minimum increment is 16 MB if you have changes on the volume. This is expected. > Mounting a snapshot requires the generation of a new UUID for the file > system in order to be able to use it. Perhaps this is a XFS limitation, > but unlike ZFS they aren't immediately available. We need to perform this > action extensively to backup file systems and allow for quick data > recovery. > This is not Equallogic problem, it's a limitation/feature of the filesystem. Taking snapshots in the Equallogic storage array takes only seconds, and the snapshots are immediately available. > There is no GNU/Linux interface to automating the snapshot process. Sure > there is a telnet interface but it changes from version to version. I > know because I've spoken with engineers to discuss this issue. I wrote > software to talk to the EQL using the interface. There are talks of an > SDK for developers but nothing has materialized. > I think Equallogic provides Perl samples how to take snapshots from Linux/Unix scripts. I remember going through the scripts earlier. So you can definitely integrate EQL stuff to your Linux environment. > Don't get me wrong, it's a great device for cheap storage compared to > competitors but there are obvious limitations that you need to address in > your requirements if you intend to deploy it. > Well.. the stuff you mentioned isn't really Equallogic specific. It's general stuff you need to sort out with any storage. -- Pasi