Hi, my opinions below:

     1. With the RAID 5 at AIX level, should a second, synchronized  copy
     of DB volumes is required.

     This depends your current situation. How important is that the TSM server 
be available? 
     Can be it down for a day if two disks fail? I'd say this is one step 
better than no mirroring or 
     protection. FYI: I use RAID 1, but my DB is small relative to yours.

     2. If I do not keep a second copy and take daily full backup, would it be 
RISKY.
   
     See above. But basically you would lose everything from the last full 
backup.

     3. Configuring RAID 5 at this juncture, would anybody see any pitfall 
ahead.
   
      No. You can backup the database, shutdown TSM, create the array 
(destroying your old LV's) and 
     restore the database.

Some questions you might consider:
     1. Can you afford the RAID 5 performance hit? If you make a small array, 
ie 5 or 6 disks, 
         those 18 G disks aren't going to do very well. Are you using SSA? 
         Read the Advance Serial RAID Plus Planning Guide. If you have to, make 
one array only with your 12 disks.
     
     2. RAID 0 for disk pools is much better, from personal experience RAID 0 
does very well here. 
         It would save you a lot of space, and it is very fast for reads and 
writes. Yes, it doesn't have any protection but that's ok.

     3. It seems odd IMHO that you have an 80GB DB but only 56GB for disk 
pools. Are you storing too many versions or files???

Miles



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Miles Purdy 
Miles Purdy 
System Manager
Farm Income Programs Directorate
Winnipeg, MB, CA
purdym AT fipd.gc DOT ca
ph: (204) 984-1602 fax: (204) 983-7557
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>>> mahesh.babbar AT ST DOT COM 22-Apr-01 2:53:24 AM >>>
>>> mahesh.babbar AT ST DOT COM 22-Apr-01 2:53:24 AM >>>
     Hi all,

     Environment:

     NSM 3466, RS 6000, AIX 4.3.2 , TSM version 3.7.4,

     12 x 18.2 GB disk ( for DB and Diskpool Volumes)

     My current DB is of 80 GB size and is alarmingly utililized ( 95
     %).The DB volulmes are mirrored inside TSM ( Second Copy).

     Therefore another 80 GB space is being used for the second copies. In
     order to have more usable space for DB, a suggestion has been mooted
     to go for RAID-5 at the hardware level.

     IBM's version is that since a second copy MUST be kept , going for
     RAID 5 shall require more disk space. Now my question is:

     1. With the RAID 5 at AIX level, should a second, synchronized  copy
     of DB volumes is required.

     2. If I do not keep a second copy and take daily full backup, would it
     be RISKY.

     3. Configuring RAID 5 at this juncture, would anybody see any pitfall
     ahead.

     Any comments are welcome!

     Regards

     MAhesh