On Wed, Dec 12, 2018 at 12:50:47PM -0500, Mike Snitzer wrote: > On Wed, Dec 12 2018 at 11:12am -0500, > Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > > Does it really make sense to enhance dm-snapshot? I thought all serious > > users of snapshots had moved on to dm-thinp? > > There are cases where dm-snapshot is still useful for people. But those > are very niche users. I'm not opposed to others proposing enhancements > for dm-snapshot in general but it is definitely not a priority (Google's > dm-bow is an example of a case where dm-snapshot may get extended to > fulfill google's needs). I would expect that dm-snapshot will be used quite a lot for short-lived snapshots (that only live during a database backup or an fsck run). I would hardly call that a "niche use case". One other major advantage that dm-snapshot has is that you can take a snapshot for any LVM volume. For dm-thinp you have migrate your storage to a thinp pool, and that adds a fair amount of friction to users migrating to dm-thinp. - Ted
