RMAN backup slows database performance to a crawl
Date: Thu, 10 Jul 2008 16:16:54 -0400
I have a 10.2.0.3 database running on Solaris 9. The database is about 1TB with 900GB of that in a single tablespace which is a single bigfile datafile. Whenever there's a RMAN backup running of the database performance slows to a crawl. I have some MV refreshes that goes from 3-4 minutes with no backup to 30 minutes when the backup is running.
Checking an AWR report I noticed that the "Av Rd(ms)" column of the tablespace IO stat for that tablespace is at 671ms (Yikes!) when the RMAN job is running and a much more normal 3.6ms when it's not.
The difference is so striking it almost looks like a bug.
Has anybody seen this or have any idea why that happens?
I'm going to fix that monster tablespace and split it into a few smaller tablespaces, but I'm wondering if this is a bug.