Using backupsets for disaster recovery

If you only use backupsets as a replacement for archives, then skip this chapter, but if backupsets are your prime medium of restore in a disaster situation, then there are some point to be aware of.

If you create a backupset that contains ALL the files from a node, then by restoring this set completely, you will overwrite the system part of your node. (c: for windows, rootvg for AIX etc. etc.)

This is probably not what you want. In a disaster restore situation, you will normally restore the system files from an image backup or through normal OS installation.
Afterwards you want to restore ALL OTHER files.

You CAN do this using a backupset, but if you want to restore only part of a backupset, you will have to run the complete retrieval process for each desired filesystem. Each invokation of "restore backupset" can only hold one filespec and will require a full read of the entire backupset, even though you are restoring only a few Mbytes.

It may take several hours to run through a large backupset, so if you have to do this 10 times, because you want to restore 10 different filesystems, the time involved may be just too much !

There are two solutions to this:

1. When you generate the backupset, specify all the desired filesystems on the "generate backupset" command. This way you only get the filesystems you want and can restore them all in one restore pass. BUT, it requires a lot of discipline to maintain the "generate backupset" commands. Whenever a server has a new filesystem added to it, you must go into your script or wherever you keep the generate command, and update it. Can you be sure that you are always notified about the new filesystems added to your servers and can you be sure that the backupsets will really contain ALL the filesystems needed for disaster recovery?

2. Logically split each server that you backup into two nodes. Backup all the system files using one nodename (nodeA) and backup all other data using another nodename (nodeB).

Now, when you generate the backupset, generate it for all filesystems (*) for nodeB only. The backupset will then contain all non-system files and can be restored in one pass.