External backup/restore - an idea - comments please

Hello everyone. Last week we've had sort of trouble - one chunk went offline after two mirrored disk crashed simultaneously (which was admitedly our fault). No problem, we take backups every night and continously backup logical logs so everything was in place for warm restore (it was non-critical dbspace residing on that chunk). But, we've had problems with backup server and it's tape library. Fortunately, all went well and restore was successful. Of course, that posed a question: what if backup server was unavailable? I read through Backup and Restore Giude and started playing with external backup/restore. At the moment we're using onbar for backup/restore with Legato Networker as storage manager. Informix (version 10.00FC3) uses exclusively raw devices. My idea was to be able to restore (to some extent at least) an instance even if the storage manager was unavailable. The procedure described in guide is clear to me, I just want your opinion on my conclusions, which are as follows... 0. Everything that's supposed to be backed up needs to be dumped in filesystem and copied to remote host (which is nowhere near current backup solution). 1. After blocking the instance I have to dump all chunks for all dbspaces to filesystem, and also the previous and current logical log(s) and then move it to remote host. 2. Since onbar can't be used to back up logical logs to filesystem (or at least I wasn't able to find the way to do it) I have to use ontape (which can do it in v10). 3. After ontape -a finishes, it marks all logical log(s), up to the current one, as backed up. That means onbar will not back them up later! 4. The previous step isn't that bad since after external backup (and unblocking the instance) I'll take regular scheduled backup with onbar (level 0, 1 or 2, depending on the day of the week) and only logs that gets backed up after that backup are needed in case of regular restore. 5. All of this I plan to do automatically through the script called from cron, during the period of lowest activity. So, before I start thorough testing my question is: how does this all sound? Is this a valid way to do something like this or am I missing something important? Thanks everyone.

I read a case study about this awhile back but I haven't tried it so I am only giving knowledgable conjecture not information gathered from real experience. So take it for what it is worth. I hope this fosters conversation and debate so I can correct any misunderstandings that I have because we are also thinking about doing this but we haven't gotten to the research stage. Is this what you are talking about: onmode -c block <get permanent copy of chunks in some way> onmode -c unblock The onmode -c puts all of the chunks into a consistent state and the block keeps them there until you give it the unblock command. During the blocked time you can copy every chunk to a file, or tape. If you have drives that have a double mirroring scheme you can break one of the mirrors for each drive and unblock the server and then backup the now unmirrored drive. This method gives you basically instant, as far as your users know backups. After you copy off the unmirrored drives you can remirror the drives. I guess you can do this with single mirrored drives but during the copy phase the database isn't mirrored. When I say mirrored I mean OS or drive vendor mirroring. I know EMC had SANS that did double mirroring for this kind of backup. I would suspect others would have this technology also. I don't think that you need to do anything with the current and previous logs. This is because these have been applied to the dbspaces that you have just backed up. Now this doesn't solve point in time backups using the logs. You can continue using onbar to backup the logs. Then to do a restore you copy everything from your external backup and then you do a onbar -r -e [-t <time> | -n <log>] [-O] [-f <filename> | <spaces>] to apply the onbar log backups. onbar will automatically figure out which logs to apply to get to the point in time that you want. I wonder now if you have backed up your logs with ontape can you do an onbar physical restore and then an ontape logical restore? If so then do an onbar -r -p -e ... then apply the logs that you need using the ontape -l command. It seems like you can but I don't actually know.