How BLI works with NetBackup for DB2 (UNIX)
NetBackup supports BLI full backups and BLI incremental backups of DB2 databases.
BLI backup supports two types of incremental backups: differential and cumulative. Full, differential incremental, and cumulative incremental backups are specified as part of the policy schedule configuration. When a restore is performed, NetBackup restores an appropriate full backup. Then it applies the changed blocks from the incremental backups.
Restoring any of the incremental backup images requires NetBackup to restore the last full backup image and all the subsequent incremental backups. The restore process continues until the specified incremental backup image is restored. NetBackup performs this restore process automatically, and it is completely transparent. The media that stored the last full backup and the subsequent incremental backups must be available, or the restore cannot proceed.
Note that restoring a file rewrites all blocks in that file. The first subsequent differential incremental backup and or all subsequent cumulative incremental backups back up all the blocks in the restored file. After an entire database is restored, the first subsequent backup results in a full backup.
The restore destination can be a VxFS, UFS (Solaris), JFS (AIX), or HFS (HP-UX) file system. The destination VxFS file system does not need to support the Storage Checkpoint feature to restore files. However, a VxFS file system with the Storage Checkpoint feature is needed to perform BLI backups of the restored data.
This topic uses the following terms to describe BLI backups:
Full Backup.
A backup in which NetBackup backs up each database file completely, not just data blocks that have changed since the last full or incremental backup.
Cumulative BLI Backup.
This type of backup is a backup of all the changed blocks in the database files since the last full backup. A cumulative BLI backup image contains only the data blocks of database files that changed since the last full backup. A cumulative BLI backup can reduce the number of incremental backup images that must be applied during a restore operation. This speeds up the restore process.
Differential BLI backup.
A backup in which NetBackup performs a backup of only those data blocks (within the database files) that changed since the last backup. The previous backup can be of type full, cumulative incremental, or differential incremental.
When NetBackup initiates BLI backups, it creates, manages, and uses the appropriate Storage Checkpoints of the filesystem(s) hosting the DB2 container files. These Storage Checkpoints identify and maintain a list of modified blocks.