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BACKUP , RECOVERY and archive log handling in RAC

Here are few basic points to consider about safe backup and recovery in RAC environment :

  • If DB running in archive log mode then archive logs should be placed on a single location(say single ASM directory) in shared disk so that if you ever needs to recover then you do not need to copy all archive logs to a single location or supply archive log file names manually for each log sequence#. Configuring Flash recovery area is so good option for RAC databases.
  • If you have less storage available or you want faster archiving only then you should consider archiving logs to local disks of nodes.                                                                                           
  • In case all instances crashes(power failure in data centre) then you should bring all nodes one by one. As this way it is not only cluster ware will have safe recovery but also  Database crash recovery will also be safe. 
  • Configure RMAN control file auto back-up feature also to shared disks (say OCFS file system,if applicable) as this will allow control file to be restored from any node and hence so recovery also.
  • As RAC instances has more shared pool available than single instance you can increase large pool size to increase RMAN buffers for faster backup so you may multiplex more files in backupset and parallelize more if enough CPUs available but remember higher multiplexing can potentially slow down restore.

  • To benefit from more CPUs available in RAC than single instance database backup channels can be opened across all RAC nodes this when combines with benefits of compressed backup sets speeds up backup   

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