Hi Luc

Normally, the primary factor isnt how many volumes you have. Its rather 
dependent on how many physical volumes you have your database on. Physical 
volumes can be either disks in your machine or LUN:s assigned from a 
central disk. If you're using SAN attached LUN:s, you should not count the 
physical disks you're using in your SAN disk rather the number of LUN:s, 
as each LUN:s has it's own write/read queue.

According to what I've seen, using between 8-12 database volumes gives a 
good performance. You should however spread them across at least 4-6 
disks, preferable 8-12 disks for optimum performance. When it comes to 
RAID I would recommend using RAID-1 or RAID 0+1. RAID-5 normally gives a 
slight performance hit during write operations due to the RAID-5 parity.

Remember that mirroring your database using hardware or operating system 
will not entirely protect your database against faults. The only mirroing 
solution that protects you against for example partial writes is using the 
built-in database and log mirroring facility within TSM.

I would not recommend you to use only one physical disk with one database 
volume. That would probably decrease your database performance.

Best Regards

Daniel Sparrman
-----------------------------------
Daniel Sparrman
Chef Utveckling & Drift
Exist i Stockholm AB
Propellervägen 6B
183 62 TÄBY
Växel: 08 - 754 98 00
Mobil: 070 - 399 27 51



Luc Beaudoin <lbeaudoi AT IS.JGH.MCGILL DOT CA> 
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
2005-01-20 17:20
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Subject
TSM DB Volumes






Hi all

I'm reading on how to delete DB volume ... and I'm a bit confuse ...
In the Admin book .. they take 4 small volumes and move them to one big
one ...
Is there a best practice or advantages to have 1 big volume or 5 small
ones ????

In my case I have 4 volumes of 4GB and 1 of 20GB .. I would like to put
them al together in one big volume ..

Any ideas ??

thanks again

Luc