What Device Must Logical-Log Backups Use?

The ontape utility uses parameters defined in the ONCONFIG file to define the tape device for logical-log backups. However, consider the following issues when you choose a logical-log backup device:

• When the logical-log device differs from the backup device, you can plan your backups without considering the competing needs of the backup schedule.
• When you specify /dev/null as the logical-log backup device in the ONCONFIG parameter LTAPEDEV, you avoid having to mount and maintain backup tapes. However, you can only recover data up to the point of your most recent backup tape. You cannot restore work done after the backup. See the warning about setting LTAPEDEV to /dev/null in Using /dev/null When You Do Not Need to Recover.
• When your tape device runs slow, the logical log could fill up faster than you can copy it to tape. In this case, you could consider performing the backup to disk and then copying the disk backup to tape.