RE: restoring possibly damaged logs

As far as the informix database is concerned, your data will remain consistent and good through the rolling forward of all logs. You will not end up with a corrupt chunk. Whether or not the operations done by your programs after the chunk went in error is a question which needs to be asked. This is a determination of how well these programs handle failing SQL. You can have inaccurate data in your database due to programs having problems handling (or not handling) the errors caused by a bad chunk, but after the restore the tables will not be corrupt from the point of view of the Informix database. Hope this helps Will >===== Original Message From tam.mclaughlin@net.ntl.com ===== >Rudy Fernandes wrote: > >> Yuri Dovgart wrote: >> >> > Tam McLaughlin <tam.mclaughlin@net.ntl.com> wrote in message >> > news:385DFDD6.565979E4@net.ntl.com... >> > > We had a situation where there was a power cut, UPS kicked in and shut >> > > down informix. >> > ... >> > >> > Generally speaking, you wrong. If your chunk is corrupted (for example, one >> > of it's pages), this means engine problem, not transaction. Anyway, it >> > depends on what happends to your chunk. In your case you will lost all >> > transactions that are in your logs on disk. >> >> My understanding is slightly different. ontape -c would have copied all full >> logical logs to tape. The log that was current at the time of the crash would >> be the only one missing from the tape. Consequently, all transactions that >> were committed in that log would be lost (in addition, of course, to the ones >> that were still open at the time of the crash!). >> >> The correct procedure, of course, would have been to salvage that last log >> (and others, to play safe!) onto a different tape for use during the logical >> restore. >> >> Rudy > >Sorry if I have not explained this properly. From the continuous log (ontape -c) >we were able to restore to the last log on tape before the crash. After the crash, >the server came back up and automatically started informix but not a continuous >log. When I came in on the morning, some cron jobs had been running during this >tme (2:30 am - 9 am). I shut down the engine and eventually done a restore. The >programs running after the crash would have generated transactions and filled up a >few logical log files despite their being a corrupt chunk. At the restore I had >the option to backup these current logs for use in the restore later but I did not >roll forward the current logs (which would have been on a second log log tape) as >I thought it best to restore to the log log file just before the >crash. This way i def knew there would be no corrupt chunks. But would there have >still been a corrupt chunk or could I be 100% positive that the chunk was ok and >the integrity of the system was ok if i had restored the log logs completed while >there was a bad offline chunk ? ------------------------------------------------------------ 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/ ------------------------------------------------------------