Planning disaster recovery

The premise for disaster recovery is that you will have copies of all your vital data sets stored at a location separate from your computer site and that a computer system of approximately the same capabilities will be available to be used to resume operations. Consider what this implies:

• You must have a copy of all your system control data sets stored at the off-site location. System control data sets change every time maintenance is applied, which for some installations is weekly or biweekly, so having automated scheduled backups are recommended. You can also dump the data sets by command whenever necessary.
• You must have copies of all your vital user data sets. You can use SMS to ensure that all of the vital user data sets are stored on the appropriate DASD volumes. You can provide these copies by using the DFSMShsm ABACKUP function.
• You must have copies of your ML1 volumes in order to recall any vital data sets that have migrated to ML1. You can use the DFSMShsm ABACKUP or automatic dump functions to provide these copies of DASD ML1 volumes.
• You must have copies of your ML2 volumes in order to recall any vital data sets that have migrated to ML2. If you use DASD for ML2, you can provide these copies by using the DFSMShsm ABACKUP or command dump functions. If you use cartridge-type, single-file-format tape for ML2, you can use the duplex tape option when creating the ML2 tapes, or you can use other DFSMShsm disaster backup facilities as discussed in this topic. ABACKUP can be used for ML2 tape data sets as well.
• You should have copies of your backup volumes in order to reconstruct your user volumes. If you make copies of your backup volumes, you can make fewer automatic dump copies of entire user volumes. You reconstruct the user volumes from the combination of the latest dump copy and the incremental backup versions of data sets made after the dump copy was made. If you use DASD for backup, you can provide these copies by using the DFSMShsm ABACKUP or command dump functions. If you use cartridge-type, single-file-format tape for backup, you can use the duplex tape option when creating backups, or you can use other DFSMShsm disaster backup facilities as discussed in this topic.
  Note: ABACKUP cannot be used for incremental versions stored on backup DASD. Only full volume dumps can provide offsite copies of data on backup DASD.
• You must have VTOC copy data sets for some cases. The VTOC copy data sets are required when you are restoring data from dump copies combined with incremental backup versions. By dumping ML1 volumes you have VTOC copy data sets available at the recovery site.
• You need a set of instructions for reconstructing the system and resuming operations.