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(a)infradead.org> 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