On Wed, Feb 02, 2005 at 11:02:49AM -0500, Kristina Clair wrote: > I have been told that dm_snapshot is still experimental in the 2.6.10 > kernel, and I was advised not to have more than one snapshot created > at a time for the same logical volume. Each snapshot is independent and keeps its own separate copy of changes, so as you increase the number of parallel snapshots you quickly affect performance. This has always been the case for LVM and device-mapper snapshots. Daniel Phillips is working on a clustered snapshot implementation which at the same time addresses this issue, allowing parallel snapshots to share their metadata.
> Basically I am just wondering what the potential problems are with > dm_snapshot. Is there anything particular that I should look out for? There are numerous memory allocation issues with the current dm-snapshot implementation: in simple terms, devices or your machine can lock up, and your system is especially vulnerable when snapshots are manipulated (create/activate) and when your system is under load. We think we understand the most important problems and are gradually fixing them, but this is not a quick process because the changes have a significant impact on the LVM2 and EVMS code bases (complex sequences of ioctls have to change). Join the dm-devel mailing list if you want to monitor progress. Alasdair -- [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
