You are exactly correct: modeling what will be rather than what is can be 
tricky.  The problem really boils down to not having enough data to really play 
with it adequately.

I can tell you from experience on probably 200 TSM servers (Windows 2003 based, 
which is just fine all of you AIX heads!) that your overall scheme is good.  
One additional, I like to run initial backups to SAS drives using a storage 
pool of device class disk.  Don't protect those drives simply use JBOD as you 
will migrate the data out of them fairly soon either to tape or file device 
class disk.  Use RAID5/6 for your SATA drives (We generally use 6 drive RAID5 
sets in 12 bay shelves and 8 drive in 16 bay shelves) and keep a smallish 
number of simultaneous backups to pools there as large numbers of backups 
thrash the RAID set something awful.

Our STORServers almost always have this mix of storage pool options for our 
customers to use: SAS 15K JBOD, SATA 7.2K RAID and some tape.  DB/LOG on SAS 
using best practices.

Next thing to consider is your V6.2 upgrade next spring.  You gotta count on 
needing more space than you have allocated currently to the DB/LOG volumes.  
Probably 3-6x is a good guess but we're all still learning.  And probably more 
spindles than you might consider for V5.  The shelves we offer have the ability 
to mix and match SAS and SATA but I'm thinking for you a whole shelf of SAS at 
least and then SATA. I don't think you really need to much intelligence or 
features in the shelves themselves as you have plenty of options with TSM to do 
what you need to do.

How much data do you backup today?  How many clients simultaneously? If you 
want to take this private, give me a call.  I have a pretty good idea how to 
size this if I have some more information.  Perhaps can save you a testing step 
(testing costs money that you could spend on additional storage...).

Thanks,

Kelly Lipp
CTO
STORServer, Inc.
485-B Elkton Drive
Colorado Springs, CO 80907
719-266-8777 x7105
www.storserver.com


-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Michael Green
Sent: Tuesday, August 04, 2009 10:06 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] I'm getting new disk storage.

I know performance benchmarking is an art. And asking questions like
"how can I test this new storage" may bring a smile on face of some of
you. But still...

The time has come and I need to replace the disk storage underlying
the DB/DISKCLASS/FILECLASS files. I'm going to test two storages from
Infortrend and DDN. Both storages allow mix and match of SAS (for
DB/LOG) and SATA (for DISK/FILECLASS) drives.
Both will be FC 4Gb attached.
I've been thinking about replicating my biggest TSM server (Linux
based) on a server that has been put aside for this purpose.  I'll
load DB/LOG onto SAS drives and some FILECLASS volumes onto SATA
drives and time the following workloads:
- expiration
- db defrag
- Reclamation

To be honest I am not sure I know how to properly set up such testing
environment. I'm concerned that my tests will not be representative
enough and will not indicate the actual performance that I'll observe
after the storage system will become production.

Your thoughts on this topic are much appreciated...
--
Warm regards,
Michael Green