LBU_PRESERVE error message

Hi, If I do oncheck -pr I can see this error message within: ... LBU_PRESERVE 0 ONCONFIG config file error on element LBU_PRESERVE. Value in reserved page: 0 Value in config file: 1 ... But I put "Y" some times ago, mayby by editing onconfig file directly. Is that the reason ? Why aren't both synchronized yet ? Which is the right one ??? BTW, what happens in a long transaction with LBU_PRESERVE and what can I do in order to make it carry on ? by adding more logs in that moment ? is that possible ? Another thing. I configured logs of 500 size but the output shows of 250 size. Why ? Ok, Thanks a lot, Manel Falcó

Manel Falc' i Aige wrote in message <3985954b.28201260@news.bcn.ttd.net>... >Hi, >If I do oncheck -pr I can see this error message within: > >... > LBU_PRESERVE 0 >ONCONFIG config file error on element LBU_PRESERVE. > Value in reserved page: 0 > Value in config file: 1 >... > >But I put "Y" some times ago, mayby by editing onconfig file directly. >Is that the reason ? Why aren't both synchronized yet ? >Which is the right one ??? The one that is right is value in the Reserved Page. You need to bounce the Informix Instance for the change in the onconfig file to take effect. > >BTW, what happens in a long transaction with LBU_PRESERVE and what >can I do in order to make it carry on ? > by adding more logs in that >moment ? is that possible ? >Another thing. I configured logs of 500 size but the output shows of >250 size. Why ? The output of onstat -l is in pages so that is why you see 250. i.e Multiple by 2K. > >Ok, Thanks a lot, >Manel Falc' >

"Manel Falcó i Aige" wrote: > > Hi, > If I do oncheck -pr I can see this error message within: > > ... > LBU_PRESERVE 0 > ONCONFIG config file error on element LBU_PRESERVE. > Value in reserved page: 0 > Value in config file: 1 > ... > > But I put "Y" some times ago, mayby by editing onconfig file directly. > Is that the reason ? Why aren't both synchronized yet ? > Which is the right one ??? Changes to the onconfig file ONLY take place when the server is bounced with the sole exception of the TAPE* parameters and, IFF the change is made using onmonitor instead of an editor, the LTAPE* parameters. > BTW, what happens in a long transaction with LBU_PRESERVE and what Same thing that happens without it except that there will always be one full logical log file empty if a long transaction rollback fills all of the logs trying to rollback. Then you can shutdown, change LBU_PRESERVE to 0 and have a reasonable expectation that there will be enough logspace in that one remaining log to complete the rollback during fast recovery. > can I do in order to make it carry on ? by adding more logs in that > moment ? is that possible ? No. > Another thing. I configured logs of 500 size but the output shows of > 250 size. Why ? Onstat shows pages but onparams and the ONCONFIG file requires KB so onstat will always show 1/2 or 1/4 depending on your platform. Art S. Kagel

Thanks Art, only one doubt as usual ... >Changes to the onconfig file ONLY take place when the server is >bounced with the sole exception of the TAPE* parameters and, IFF the >change is made using onmonitor instead of an editor, the LTAPE* >parameters. Well, I think I changed it via onconfig file, but I said then to my customer to shutdown after finishing working that day ... and he did > >Same thing that happens without it except that there will always be >one full logical log file empty if a long transaction rollback fills >all of the logs trying to rollback. Then ***you can shutdown***, change >LBU_PRESERVE to 0 and have a reasonable expectation that there will >be enough logspace in that one remaining log to complete the rollback >during fast recovery. When fails, it tries to rollback but if it cannot ... what happens with the transaction. Which is its state ? shall it commit it the rest ? So, when you say "you can shutdown" is immediately after the fail occurs ?? if not, what happens if you shutdown after a while ? can users go on ? > >> can I do in order to make it carry on ? by adding more logs in that >> moment ? is that possible ? > >No Would be good >

"Manel Falcó i Aige" wrote: > > Thanks Art, only one doubt as usual ... > > >Changes to the onconfig file ONLY take place when the server is > >bounced with the sole exception of the TAPE* parameters and, IFF the > >change is made using onmonitor instead of an editor, the LTAPE* > >parameters. > > Well, I think I changed it via onconfig file, but I said then to my > customer to shutdown after finishing working that day ... and he did Then it should have taken effect. > >Same thing that happens without it except that there will always be > >one full logical log file empty if a long transaction rollback fills > >all of the logs trying to rollback. Then ***you can shutdown***, change > >LBU_PRESERVE to 0 and have a reasonable expectation that there will > >be enough logspace in that one remaining log to complete the rollback > >during fast recovery. > > When fails, it tries to rollback but if it cannot ... what happens > with the transaction. Which is its state ? shall it commit it the > rest ? When a long transaction begins to rollback there is no other immediate effect. After a while the rollback records and other transactions may cause the logs to reach the LTXEHWM which will halt all other transactions in an attempt to reserve the remaining log space for the rollback of this long transaction. At this point no update processing is occurring for ANY other thread. If the logs fill to the point where there is no space for any more rollback records in backed up logical logs, or except for one if LBU_PRESERVE is set to 1, then the engine will hang waiting for you to backup the logical logs. In general this cannot be done because there is no room in the logs for the checkpoint and begin archive records to be written either so the engine is hung for updates. Soon the next checkpoint period will occur and that will block readers also until the checkpoint record can be written and it cannot since there is no room so the engine goes into CHKPT REQ mode and hangs altogether. At this point if you have set LBU_PRESERVE you can run onmode -ky and shutdown the engine then clear LBU_PRESERVE to release the last logical log for reuse, and restart the engine to single user mode so you will have a chance to complete Fast Recovery and complete the pending rollbacks and then backup the logical logs. If you have NOT set LBU_PRESERVE you are hosed and have to call tech support to truncate the last logical log or two on disk to allow the rollbacks. In this case some committed transactions MAY be lost or rolled back due to the truncation but this is unlikely unless you have the LTX parameters set way too low. > So, when you say "you can shutdown" is immediately after the fail > occurs ?? if not, what happens if you shutdown after a while ? can > users go on ? See above. > > > >> can I do in order to make it carry on ? by adding more logs in that > >> moment ? is that possible ? > > > >No > Would be good Unfortunately it's a catch 22. To add logical logs you have to a) log that fact, b) create a level 0 archive to enable the new logs. Unfortunately there is no logical log space free, in this case, to enable you to perform these two tasks so... Art S. Kagel