Block tracking for faster RMAN backups

In an effort to make the RMAN backups for a database run in less time and using less CPU, I turned block tracking on.
en español

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;
FILENAME                              STATUS
—————-                      —–
+FRA_CCBPRD/blocktrack_.log      ENABLED

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.
BEFORE AFTER
Duration
2 hours 36 minutes
CPU usage 100% 25%
Size
8GB 7GB

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