RE: Difference Between RMAN Incremental and Full Backups - Driving me Nuts!
Date: Thu, 17 Jul 2008 09:49:45 -0700
I have been running incremental backups on AIX5.3 with CIO for years now and haven't had any problems, but I'm also running 10.2.0.2 database and Netbackup, so not exactly the same setup. In 10g, you don't have to mount the filesystems with the cio option - you just set filesystemio_options=setall and then Oracle opens the datafiles with the CIO flag.
I found bug 4034775 on Metalink which talks about some performance problems with backups on AIX and they suggest setting AIXTHREAD_SCOPE=S so you might want to try that if you haven't already. I do have it set in my environment.
I don't have any idea why the full would run so much better than the incremental. Did you try implementing the block change tracking file? Any improvement from that? It should dramatically reduce the number of disk I/Os required for the incremental backup and in my case it reduced my backup runtime from about 2 hours to 2 minutes.
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