Unix Backup and Recovery

Recovering Informix

Recovering Informix is much easier than recovering other databases. One reason is that the commands to actually perform the recovery are simple—there is only one argument for ontape and only two arguments for onbar. This section covers just about any recovery scenario that you might find yourself in, yet it has fewer than 20 main steps.

Another reason that Informix recoveries are simple is that the sysmaster database, physical log, and logical log are considered critical. In order to recover one of them, you have to recover all of them. In Oracle, for instance, there are four or five different recovery tactics that you can use, depending on which one of these objects is damaged. With Informix, there is only one recovery tactic.

The Informix recovery procedure does not assume that you know why your database went down. It does assume that you have been making backups via ontape or onbar. It also assumes that if you are using ontape, you know which tapes or files contain the latest level-0 and/or level-1 backups, as well as the location of all logical log backups since your last physical backup. If you are using onbar, this procedure assumes you know how to use your storage manager well enough that you know how to respond to its prompts for any media that may not be in an autochanger. In short, all media management is up to you.

The following examples use ontape . The example hostname is curtis, and the instance name is crash . The archives are being sent to disk ...