Space requirements for Db2 protection
Before you start backing up Db2® databases, ensure you have enough free disk space on the target and source hosts, and in the vSnap repository. Extra free disk space is required on the volume groups on the source host for creating temporary Logical Volume Manager (LVM) snapshots of the logical volumes that the Db2 database and log files are stored on. To create LVM snapshots of a protected Db2 database, ensure that the volume groups with Db2 data have sufficient free space.
LVM snapshots are point-in-time copies of LVM logical volumes. They are space-efficient snapshots with the changed data updates from the source logical volume. LVM snapshots are created in the same volume group as the source logical volume. The IBM Spectrum® Protect Plus Db2 agent uses LVM snapshots to create a temporary, consistent point-in-time copy of the Db2 database.
The IBM Spectrum Protect Plus Db2 agent creates an LVM snapshot which is then mounted, and is copied to the vSnap repository. The duration of the file copy operation depends on the size of the Db2 database. During file copying, the Db2 application remains fully online. After the file copy operation finishes, the LVM snapshots are removed by the IBM Spectrum Protect Plus Db2 agent in a cleanup operation.
For AIX®, no more than 15 snapshots can exist for each JFS2 file system. Internal and external JFS2 snapshots cannot exist at the same time for the same file system. Ensure that no internal snapshots exist on the JFS2 volumes as these snapshots can cause issues when the IBM Spectrum Protect Plus Db2 agent is creating external snapshots.
For every LVM or JFS2 snapshot logical volume containing data, allow at least 10 percent of its size as free disk space in the volume group. If the volume group has enough free disk space, the IBM Spectrum Protect Plus Db2 agent reserves up to 25 percent of the source logical volume size for the snapshot logical volume.