HP Data Protector IDB Purge Best Practices

Table 2.

Windows HP-UX PA Risc HP-UX IA 64

Data Protector 6.0 DPWIN_00385 PHSS_38404 PHSS_38405

Explaining QuickMediaFormat

In the course of a backup, DP’s Backup Session Manager (BSM) may need to overwrite a media. For

media containing a large number of objects and corresponding media positions the purging of this

information from the IDB can put a high and sustained load on the process that manages the DP IDB

(known as RDS). This sustained load on RDS may give the false impression that DP has hung. This

behavior is observed more today than by DP users in the past, because of the large volume of data

modern media can hold.

If QuickMediaFormat is set to 1 in the global file, DP will only purge a defined number of records

during the backup or when a media is formatted. Other obsolete records will be removed when a

purge mpos command is run. If the QuickMediaFormat is not set, all the records will be purged from

the database during the backup.

The command omnidbutil -purge -mpos can be run to remove the object versions and media

position records for the overwritten tapes. Both DP 6.11, and DP 6.0 with the Cell Server patches

mentioned in the preceding table, have omnidbutil -purge –mpos included as part of the Daily

Maintenance. So, this purge will automatically take place every day as long as Daily Maintenance

has not been disabled.

Example of messages seen at the command line

omnidbutil -purge –mpos

Starting Purge for formatted medium (-mpos)

Successfully completed Purge for formatted medium (-mpos)

DONE!

Note:

QuickMediaFormat=1 should not be set at the same time as

DbPurgeExpiredOvers=2.

Tuning Quick Media Format with FormatOversPerTransaction

If Quick Media Format is set to 1 the number of Object versions (overs) that will be deleted from the

IDB for a media during a backup is tunable with the global setting FormatOversPerTransaction. If DP

needs to overwrite a tape during a backup it will remove a maximum number of overs as defined by

FormatOversPerTransaction. Once that number have been removed from the IDB, the backup

will continue. Any remaining obsolete overs will be removed later as part of the daily maintenance (or

manually by running the omnidbutil -purge -mpos command). The default value for

FormatOversPerTransaction is 50.