In an effort to make the RMAN backups for a database run in less time and using less CPU, I turned block tracking on.
For more information on block tracking, check out the Oracle documentation.
Originally, the RMAN backups
- Took 2 hours.
- Maxed out the CPU – the disk was 100% busy.
- Wrote out 8 GB of uncompressed files.
To turn block tracking on:
SQL>alter database enable block change tracking using file ‘+FRA/blocktrack_.log’;
NOTE: This is a RAC (Real Application Clusters) database and the block tracking file needs to be in a place where all nodes can read it. This database uses ASM (Automatic Storage Management), so I put it in the +FRA (fast_recovery_area) diskgroup, which can be accessed by all the nodes in the cluster.
To verify that block tracking is turned on:
SQL>select filename, status from v$block_change_tracking;
After block tracking was turned on, the first RMAN backup ran long and heavy as usual, but the next one was better:
- Took 36 minutes.
- CPU usage was not maxed out.
- Wrote 7GB of uncompressed files.
|2 hours||36 minutes|