A client asked me to refresh a test database from a production including data and structure. Production database was 800GB and RMAN level 0 backup was taken every day.
In the first step, I tried to restore a 4GB datafile from tape to have better picture on how long the whole exerxise would take. Result was surprising!.
Restore of 4GB datafile took 15 minutes. Simple math showed me that whole restore should take more than 46 hours !!!
This time obviously was not acceptable to the client.
While I was searching more, I found that whole database backup just takes only 7 hours.
As the first guess I was suspicious to Veritas catalog and how it looks up backups.
I finally found metalink note 309891.1 which strongly recommends to put specific backup format to improve RMAN restore using Veritas netbackup.
Oracle recommends to put %t (lower case) at the end of backup format (Only at the end) to ensure uniqueness and optimal performance.
Interestingly, when backup format was changed to 'datafile208__%d_%u_%s_%T_%t'. the whole restore was done in 8 hours.
This workaround is applicable to 126.96.36.199 to 10.2.0.0.