"Matt Clark" <matt(at)ymogen(dot)net> writes:
> So when you take a snapshot there is no data to be copied, and when
> you release a snapshot some data needs to be written back.
Does the write-back preserve the original write ordering? In general,
what happens if there's a system crash in this state? What of errors
encountered during write-back, eg out of disk space (or is disk space
accounting still done in terms of the original volume)?
regards, tom lane