"Simon Riggs" <simon@xxxxxxxxxxxxxxx> writes: > On Fri, 2007-06-22 at 13:12 -0400, Tom Lane wrote: >> If you saw a problem I'd be inclined to question whether >> there is some upstream component (OS or disk controller) that's >> reordering writes. > Given thats exactly what they do, constantly, I don't think its safe to > say that it works since we cannot verify whether that has happened or > not. If he's trying to snapshot at a level of hardware that's behind a write-caching disk controller, I agree that that's untrustworthy. If not, ie if he's snapshotting the actual durable state of the storage system, then any problems in the snapshot indicate a problem with the database's ability to recover from a crash. So I don't think you should tell him to not worry. regards, tom lane
