External Backup without blocking the database

Hi, I would like to design a backup and restore concept for Informix with a storage cluster technology. For the backup we would use the disk mirror option of the cluster software. The storage cluster can do an atomar split on mirrored disks. So I would like to ask if I can do the external backup without blocking the whole database (onmode -c block). I think that maybe a checkpoint with (onmode -c) is ok. And after the checkpoint I would like to split all mirrored disks. The split is really atomar to all disks. So they they will be splitted all in the same time. There is no IO while the split is in progress. Is it under these circumstances possible to don't block the database? Christian Schmidt.

"Christian Schmidt" <weltraumschmidt@googlemail.com> wrote in message news:91a808d1-1dca-4b67-8154-f3ecc5ccdbcc@d1g2000hsg.googlegroups.com... > Hi, > > I would like to design a backup and restore concept for Informix with > a storage cluster technology. For the backup we would use the disk > mirror option of the cluster software. The storage cluster can do an > atomar split on mirrored disks. So I would like to ask if I can do the > external backup without blocking the whole database (onmode -c block). > I think that maybe a checkpoint with (onmode -c) is ok. And after the > checkpoint I would like to split all mirrored disks. > The split is really atomar to all disks. So they they will be splitted > all in the same time. There is no IO while the split is in progress. > Is it under these circumstances possible to don't block the database? > > Christian Schmidt. I'm a little confused here. I'm not sure what "atomar" is, or means. But ... 1. Yes, critical to external backups is that all the disks "will be [split] at the same time". "Consistency Group" is the word for this. 2. *Why* do you wish to avoid blocking the database? It's easy to script sync->block->split->unblock. Even on a database of terabytes the time between block and unblock can be a second or two at most ... 3. In your suggestion above how would you ensure that there is no i/o between the end of your checkpoint and the end of the disk split process, *except* with a blocking checkpoint??

"Neil Truby" <neil.truby@ardenta.com> wrote in message > I'm a little confused here. I'm not sure what "atomar" is, or means. I would guess from the context that he means "atomic" and this is just a minor English-is-not-his-native-language mistake. I know a lot of modern storage boxes support atomic mirror splitting. -- Kevin Cherkauer Software Engineer IBM Informix Dynamic Server -- Database Kernel