RMAN job very slow

[franco]

Oracle 9i, patch set_04,two node fail safe cluster.
I have set up, with OEM, a RMAN job in order to backup the databaase of approx 20GB.
I use RMAN with a recovery catalog.
The job run for about 4 minutes, so very good performance I think.
Now something change and the job run for about 27 minutes, the db is always the same and the job is still succesfull.
What can you suggest in order to come bak to the previous perfomance?
Where do I hava to investigate?
Please advise.
Best regards.

[marist89]

I would look at v$backup_async_io or v$backup_sync_io to see if either my input or output streams were grossly different from another day. If so, I would check for errors at the OS.