Month: November 2010

Simulating and resolving a dataguard archivelog gap


I was wondering what will happen iff some archivelog gap really happens in a dataguard environment. How to resolve it? What has to be done manually and what happens automatically due to the remote file service (fal), for example.

Well, my attempt in producing the problem goes like this:

  • verify normal operation by doing manual log switches on primary and watching the alert.log on primary and standby what happens
  • defering the remote log destination (usually #2) on primary
  • doing another manual log switches on primary that do now, don’t get shipped to standby
  • backup primary with removing all backed up archive logs from the recovery destination
  • bounce primary and standby
  • activating the remote log destination (usually #2) on primary again, doing another manual log switches on primary, watching the alert.log on primary and standby what happens

Ok, let’s follow the alert.log on primary and standby …

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Uncataloging a backupset from the rman repository


Ever seen this error message?

RMAN-06122: CHANGE .. UNCATALOG not supported for BACKUPSET

Seems you’re trying the get clean of backup sets that still exists on disk or tape but should no longer be regarded as a part of this database. What for? Well, this is quite a common requirement for rman-cloned or -duplicated databases where the rman repository (controlfile copy) originates from a seed database. Think of a standby database creation for example.

Since uncataloging backupsets is not allowed, one may test drive a change backupset ... delete;. Uurgh, this will also delete the files physically, which is clearly not the intention.

Another escape may be change backupset ... unavailable;, however, this attempt may result in ORA-19813: cannot have unavailable file ... in DB_RECOVERY_FILE_DEST. Great!

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