Conceptual Ontape Question

Lets pretend, shall we? 1. Users are actively using the system, entering data and what-not. 2. Level 0 ontape is started at 4:30pm. 3. All users are logged off at 5:30pm. 4. Ontape completes successfully at 5:45pm. Question: Was all of the data backed up? Or was some data potentially missed since users were entering data for that 45 minute period that ontape was running? I say the latter, but now I'm hearing that ontape would have picked up everything. Anyone know the correct answer? Thanks!

Yep, the backup is consistent to the first check point that is done after the ontape is issued. ontape forces a checkpoint for this purpose. If it tried to keep up with the changes that happened while it was running you might get into a situation where ontape could never finish because updates were happening faster than ontape could record them. >From what I understand the before images of pages that are changed while ontape is running and that it hasn't backed up yet, are put into the tempdb spaces so that ontape can back them up in their original state without affecting update peformance much. Of course if you make a lot of changes you can have temp space issues. natebsi@gmail.com wrote: > Lets pretend, shall we? > > 1. Users are actively using the system, entering data and what-not. > > 2. Level 0 ontape is started at 4:30pm. > > 3. All users are logged off at 5:30pm. > > 4. Ontape completes successfully at 5:45pm. > > > Question: > > Was all of the data backed up? Or was some data potentially missed > since users were entering data for that 45 minute period that ontape > was running? > > I say the latter, but now I'm hearing that ontape would have picked up > everything. > > Anyone know the correct answer? > > Thanks!

Hi, that's correct. You can check the checkpoint (and it's time) in the output of "oncheck -pr". It is the archive information page at the end of the output of oncheck. To not miss changes by users done during the execution of ontape, you have to backup the logical logs. That is what they are there for. Upon restore the logs can be restored and applied, basically "re-doing" those changes to get everything up to date. Without logical log restore you will get the state of the archive checkpoint. To have that consistent, all transactions that were open at archive checkpoint time will be rolled back. And this is done without logical log restore when using ontape. (Note: ON-Bar is different in this regard.) Regards, Martin -- Martin Fuerderer IBM Informix Development Munich, Germany Information Management Visit one of the upcoming Infobahn events in Germany to get up-to-date information on Informix products: - June 20, 2006 at the IBM Forum Muenchen - June 21, 2006 at the IBM Forum Frankfurt - June 22, 2006 at the IBM Forum Berlin For more please see: http://www.ibm.com/de/events/infobahn/ informix-list-bounces@iiug.org wrote on 05.06.2006 21:33:31: > Yep, the backup is consistent to the first check point that is done > after the ontape is issued. ontape forces a checkpoint for this > purpose. > > If it tried to keep up with the changes that happened while it was > running you might get into a situation where ontape could never finish > because updates were happening faster than ontape could record them. > >From what I understand the before images of pages that are changed > while ontape is running and that it hasn't backed up yet, are put into > the tempdb spaces so that ontape can back them up in their original > state without affecting update peformance much. Of course if you make a > lot of changes you can have temp space issues. > > natebsi@gmail.com wrote: > > Lets pretend, shall we? > > > > 1. Users are actively using the system, entering data and what-not. > > > > 2. Level 0 ontape is started at 4:30pm. > > > > 3. All users are logged off at 5:30pm. > > > > 4. Ontape completes successfully at 5:45pm. > > > > > > Question: > > > > Was all of the data backed up? Or was some data potentially missed > > since users were entering data for that 45 minute period that ontape > > was running? > > > > I say the latter, but now I'm hearing that ontape would have picked up > > everything. > > > > Anyone know the correct answer? > > > > Thanks! > > _______________________________________________ > Informix-list mailing list > Informix-list@iiug.org > http://www.iiug.org/mailman/listinfo/informix-list