RE: Fuzzy checkpoints.

>===== Original Message From Daniel Wood <dwood@informix.com> ===== >However, restoring the physical log does have one side effect that has never >occurred to me before and that is; if any pages were only partially written when >the power goes out then restoring the physical log will correct them. If the last >page of the physical log was only partially written the check of the trailing >timestamp will prevent it from being restored. > >I believe William's question is; what happens to logical recovery if it encounters >a partially written page, which may be possible if the page isn't physically logged? >The question being answered is; why do we need or not need the physical log? > >Note: Mirroring or UPS'es, common on large systems, virtually eliminating this >possibility. You are correct on what I am asking... How can mirroring prevent this?(I might see how informix mirroring could, but how could hardware mirroring handle it?) As far as UPS's go, sometimes users decide they dont like it when their PC dies in a power outage. Server is plugged into wall, PC into UPS. No word documents lost, server down ;) I imagine some O/S panics might cause a similar situation to occur. Will P.S. I realize that this chance may be small that one may encounter it, the more servers you have the higher the likelihood... ------------------------------------------------------------ This e-mail has been sent to you courtesy of OperaMail, as a free service from Opera Software, makers of the award-winning Web Browser, Opera. Visit us at http://www.opera.com/ or our portal at: http://www.myopera.com/ Your free e-mail account is waiting at: http://www.operamail.com/ ------------------------------------------------------------