On Tue, Aug 4, 2009 at 7:41 PM, Kelly Lipp<lipp AT storserver DOT com> wrote:
> 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.
>

Your suggestion of using JBOD instead of RAID for DISKCLASS data is
intriguing... I accept the reasoning behind not protecting these
drives by RAID. But how does it affect the workflow performance-wise?
What is the rational behind this? Economy (no wasted drives for
parity), performance gains?


>
> 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...).

That particular server backs up  700-1000GB  (~400K+ affected objects)
coming from just under 100 nodes nightly.
Thanks for offering me a phone consultation :) I won't bother you for
the time being, but maybe I will at a later time :)

>
> Thanks,
>
> Kelly Lipp
> CTO
> STORServer, Inc.