On 1/11/06, Ming Zhang <mingz@xxxxxxxxxxx> wrote: > On Wed, 2006-01-11 at 20:54 +0000, Alasdair G Kergon wrote: > > Efficient, unlikely with the current implemention - hence the need > > for a rewrite. > > > > > If you have 5 snapshots of the same origin, the current implemention > > takes 5 copies of the data when you change it. That approach is > > never going to scale well! And it uses lots of memory. > > yes, you are right. is there any new rewrite action proposed or planned? My understanding is that much of RedHat's Cluster Snapshot Block Device (CSNAP) core is a candidate for the dm-snapshot rewrite: http://sources.redhat.com/cluster/csnap/csnap.ps Along with other improvements, performance would be addressed with a shared exception table (tree) for all snapshots (only one copy of each exception). When I spoke with Daniel Phillips (author of CSNAP stuffs) a few months ago he said CSNAP is on the back burner until others realize just how bad the existing dm-snapshot is. He is looking/waiting for others who are willing to contribute in moving CSNAP's snapshot improvements into dm-snapshot++. Unfortunately I'd only be able to contribute testing at this time... Mike -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
