why does RMAN TDPO start such a huge amount of sessions?

[PaulKolling]

Hi,

we can see many many sessions from our RMAN TDPO Clients in our activity log over the day - not in parallel, mostly in sequence!
There are lots of nodes with more then 12000 sessions per day !
What is the reason for this and is there any possibility to prevent this behaviour of RMAN?

regards
Paul

 

[marclant]

Check with your DBAs. They are likely archiving their database logs throughout the day. That's common practice by the way.

 

[PaulKolling]

Yes indeed, they do that, I know. But why are 12000 sessions necessary for that? I think when archiving a database once in an hour - let's assume with 4 channels - there should be something around 4 sessions per pass, why 12000 ?

 

[marclant]

There's one session every time RMAN opens a channel. The answer resides with RMAN, from the Spectrum Protect server, we only see the sessions, can't tell what RMAN is doing.

 

[PaulKolling]

hm, you are confusing me a little bit - this is the first time I use this platform since many many years - has something changed here? am I in the wrong Forum? I wanted to discuss a strange behaviour of Spectrum Protect Oracle Client - why do you tell me the absolute basics and commonplaces about RMAN?
Isn't anybody else here using the Spectrum Protect Oracle Client?

 

[marclant]

You are in the right forum and I'm trying to help you.

The thing about Oracle is that there is no Spectrum Protect Oracle Client. RMAN is the client and all that Data Protection for Oracle provides is an API so that RMAN can send backups to the Spectrum Protect Server.

The point I was trying to make is that RMAN controls the backup. I am not familiar enough with RMAN to know how the internals work, but I do know that the sessions are opened as a result of activity generated by RMAN. I also know that RMAN has a fileperset options that determines how many files are sent per backupset. If the backups are sent to a deduplicated pools, the recommended value is fileperset=1 (https://www.ibm.com/support/pages/rman-settings-when-using-tivoli-storage-manager-deduplication) and that would use 1 session per object.

This brings us back to RMAN, how is it configured? How many objects is it sending? How frequently? If the fileperset value is low and RMAN is sending a large number of objects, then it's normal to see a large number of sessions.