Here we go with target sessions again. :-)

[hermxl1]

I'm having some problems with the number of sessions on my tape drives and I ran across this response to a thread:

"TDun (TechnicalUser) Aug 1, 2003
Unlike parallelism, target sessions is not a limit. If set to 4, this means it writes the first 4 streams to that tape. stream 5 goes to th next, as does 6,7,8. 9 would go to a third (and 10,11,12).
Stream 13 would go to the first, 14, to the 2nd, 15 to the 3rd, balancing at that point. "

I'm posting to try and validate TDun's statement here only because I have not seen NW react exactly in this fashion.

My env. is a 9740 w/10 DLT7000 drives all set to 8 target sessions ( yes I know that may be high but I didn't set that up) and about 300 clients all set to a parallelism of 4. The server parallelism is set to 60.

On this server I regularly see a drive go to 14-17 simultaneous sessions but its not really uniform. With TDun's explainatin above I would expect to see more session on all drives if I have a large number of save streams active, but its typically only one or 2 drives. This makes me think that when NW rolls back to adding sessions to the first drive that it assigns another 4 or in my case 8 sessions to that drive and not adding 1 session to each drive in the list.

Anyone have any clues on this one????

Herm

 

[Chacalinc]

do you have enough tapes? I mean, you have 10 DLTs but do you have 10 tapes for the same pool?

 

[TDun]

It is also possible that you have limitations on the pools you use. If a pool specifies drives, it can only use those. This would skew the usage seen.
Likewise, if you use multiple pools, it could be skewed. My definition was based on one pool (e.g. Default).

e.g. You use pools Default and MyPool and have 2 drives. If you have a server parallelism of 48 and 16 streams for Default and 32 for MyPool, these are the numbers you will see for each drive.

It excludes cloning too. (Cloning usage obviously uses one drive for reading only).

 

[hermxl1]

Tdun, the pool idea makes sense. I needed to understand the other items that could affect the number of concurrent tape sessions.

Thanks for the info.

Herm