Re: External Backup without blocking the database

"Christian Schmidt" <weltraumschmidt@[EMAIL PROTECTED]
> wrote in message 
news:91a808d1-1dca-4b67-8154-f3ecc5ccdbcc@[EMAIL PROTECTED]
> 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 cir***stances 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??