tbzero, logs, high water marks

> TBZERO is the only way I know of. > > A released, supported tbzero would be very nice. We've needed > similar from time to time. There really isn't any other way after > Informix won't come up. > > Jim Burks jburks@promus.com > Database Administrator > The Promus Companies Watch out for that tbzero. johnl wrote a pretty scathing rebuke of the use of that program. It is truly a tool of last resort, and its use may be worse than having to restore from an archive. There is no way to guarantee the state of your data after a tbzero (or something like that.) We used to have that problem, but we learned two things: re-write deletes/purges to commit every row if the logs get filled up, manaully run the auto-backup from tbmonitor to free them. This works when the tbtape dies, and the logs fill from regular use (maybe not from a single huge event). This saved us a bunch of hassle that we didn't used to know how to deal with. Also, there are several things to keep in mind when sizing logs. Logs take up memory, and that's expensive. It is possible to have more logs than you need, adversely affecting other processes thru memory shortage. Your high water marks are important, (in online >= v.5.0) and a topic of controversy. The default settings are too high (IMHO). You need enough log space to handle your largest transaction, plus a fudge factor, plus a rollback. This means the high water mark should be <50%. This is kind of expensive, though, since it will abort a transaction that might have only needed 51%. These are some of the tradeoffs, there are others. A pretty good discussion is in the Informix OnLine Administrator's Guide, version 5.0 December 1991 from page 3-11. Good luck, __________________________________________________________________ | Clem Akins Standard Disclaimers Apply | | Reynolds Metals Co. "Climb High, Cave Deep!" | | Alloys Plant (MS #59) | | 3509 East 2nd St Internet: cwa@leia.rmc.com | | Muscle Shoals, Al Telephone: (205) 386-6783 | | USA 35661-1256 Facsimile: (205) 386-6831 | |________________________________________________________________|