Open Systems Instant Backup

As discussed in the introduction, instant open systems backup can be much easier to set up. Say you are hosting AIX data on an EMC symmetrix. All you need to do, is split off a BCV for that data, then mount it on a different server. That gives you an instant backup. Restores simply require that files are copied from the BCV back to the original server. Can it really be that simple?

Yes, almost. There are a few problems with the scenario above. If the BCV is mounted on a separate server, then what is to stop users updating it, and corrupting the backups? The BCV needs to be set up as read only. Another issue is that you will certainly want several generations of backups. Can you afford to keep 10 full copies of all your data online? You want to copy that data off to tape each day, so the BCV can be refreshed.
There is another issue, the backups will be recorded for the 'wrong' server. You need to know where the original data came from, so if you need to do a restore from tape, you can restore to the right server.

The key to this is to define unique volume names between live servers. For example, Compaq's DRM software for server clustering includes 'Clone' and 'Snapshot' commands for creating instant backups. Typically, you will have 2 or 3 live servers in a cluster, and a backup server which contains a copy of all the live data. Say your production servers are called SERVER1, SERVER2 and SERVER3, and your backup server is called SERVERB. (Yes, I know, absolutely no imagination at all). SERVERB will contain snapshot copies of all the volumes on the three production servers, but these volumes must have unique names. You run your backups from SERVERB, and they have no effect on user work running on SERVERS1/2/3.
You run your restores from SERVERB, but you have to point them to the correct live server. This is complicated slightly, as volumes can move between servers in the cluster. So, sticking with exotic naming standards, lets want to restore a file from volume VOL001, say the path name is VOL001:/data/staff/me/lotterywinner.xls
The first step is to find out which server is hosting VOL001. You can find this out by checking NT Explorer, Network Neighbourhood. You find the volume is on SERVER2. The TSM recovery command would be

 res data:/staff/me/lotterywinner.xls SERVER2/VOL001/staff/me/ -pick -inact

Your favourite backup and recovery product will have an equivalent command.

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