Using Windows compressing on TSM diskvolumes

[ghosts]

Hi all!

In my customer environment there is for the moment a lack of diskarea and the TSM diskvolumes are for the moment compressed.
I've read at some best practise not to compress TSM diskvolumes in Windows.
What's your opinion on that?
Can it be some performance issue or..

 

[max]

hi,
since you didn't mention anything about your environment, given that you have a library, you may consider saving directly to tape, avoiding diskpools, and modifying any concurrent backup you have to disk, to a sequential backup procedure of your clients (unless you have plenty of drives).
Regarding Windows compression ... I would never ever compress TSM diskvolumes.
cheers
max

 

[ghosts]

Thanks Max for your reply,

I didn't mention the customer environment because this contract (solution) is what it is. It could be better that's for sure.

Can someone please get more deeply on how compressed diskvolumes affect performance or other imortant things in TSM.

Thanks in advance!

 

[BBB]

When you say disk volumes do you just mean stgpool volumes, or doe you also include the DB&LOG volumes in that?

Compressing volumes means the CPU has to decompress any data TSM needs to read from disk, any time TSM does disk IO. This can pretty quickly swamp your CPU.

You should consider using TSM Client compression, and then not using compression of the TSM volumes. You'll probably get a better compression ratio this way, and you won't kill your TSM server. It may slow down your client backups but in many cases this doesn't really matter.

 

[heada]

BBB is spot on. Using Windows compression for disk volumes would require either it to remain uncompressed (will be uncompressed whenever TSM has it open which could be whenever TSM is running...all the time) and so gains nothing or the CPU will constantly be decompressing - recompressing the volumes which will kill performance.

By enabling client compression, the data is compressed on the client and so you get the benefit of compression without the CPU overhead on the server. Also, the data is compressed regardless of where its stored(disk, tape, etc) including during transit so it will lower your bandwidth requirements on the server.

-Aaron

 

[ghosts]

Thank you BBB and Heada,

Yes, there are disk stgpool volumes.
Now I understand what to do and why to do something about it.

Thanks again!