System Programmer Reference › Backing Up Data › Backing Up CMS Minidisks › Change Detection for CMS Backups

Change Detection for CMS Backups

When CA VM:Backup performs an incremental CMS backup, it compares a minidisk with the catalog chain on which the job is based and then:

• Backs up files that have changed since the last backup
• Backs up files that have not been previously backed up
• Records the erasure of any files that were included in a previous backup

When defining the backup job template file, the CA VM:Backup system administrator defines how CA VM:Backup detects changes during CMS backups. Depending on whether the job is a full or incremental backup job, CA VM:Backup will react in the following ways to what is specified for change detection:

• For a full backup, CA VM:Backup uses the change detection selection to determine what to save in the catalog to use for comparison during an incremental backup to detect whether data has changed.
• In incremental backups, CA VM:Backup uses the change detection selection to determine what values should be compared with the values stored in the catalog to determine whether data has changed.