Hi Alexander,

your setup is much larger than ours but I think the principles are the same. 
We have a 3575, six drives; SP2 4 silver nodes, one is the ADSM sever. We run 
Sybase.

I have a couple of comments:

1. Are you using a switch in you SP? If you are, you might check the 
TCPWindowsize on the client. I'm sure it should be 2048.

2. You might to try setting the TCPwindowsize on the server to 2048.

3. Did you make a type in the TCP_SEND and RECV? it should be 65536.

4. How many SCSI adapters do you have? How many drives are on each adapter? 
    I don't know for sure about the 3494's, but I would guess that more than 
two would hurt performance.

5. I believe that sb_max should be twice the size of the your TCPwindowsize. 
Ours is set to 4194304. Of course increase the wall (1048576).
   (2048 * 1024 * 2) 

6. What is tcp_mssdflt set to? (ours: 65536)

Miles

-------------------------------------------------------------------------------------------
----------------
Miles Purdy, System Manager
Miles Purdy, System Manager
purdym AT nisa.gc DOT ca
Net Income Stabilization Account
Winnipeg, MB, CA
(204) 984-1602


>>> Alexander Liu <aliu AT CORPNOTES01.MW-CORP DOT COM> 11-Feb-00 10:32:21 AM 
>>> >>>
Hi all,

We are running ADSM 3.1 on a R40 (6 way 200MHz) hi node in an SP2.  We are
backup up
a 1TB DB2 EEE database which is running on 24 silver nodes (2 way 332 MHz).
The SP2
is running at AIX 4.3.2 and PSSP 2.4.  The ADSM server has a 3494 attached
with 16
3590 B1A tape drives.

Our problem is that, we started out with 6 drives and completed the backup
in 12 hours.
Now that  we added 10 drives and 2 additional frames to the 3494, our
backup is actually
taking longer to complete 13-14 hours using 8 drives at a time.  The DB2
backups write directly
to tape. I am hoping to complete the backups within 9 hours or less using
up to 12 drives.

I have started playing around with the tuning values in ADSM and AIX, but
have not come up
with the correct combination. So, if anyone has any experience with a
similar setup, any help
is appreciated.

Here are our tuning settings:

SP switch settings on all nodes:
     spoolsize/rpoolsize      16777216  (16MB)
AIX
     thewall             262144
     sb_max              1310720
     tcp_sendspace       655360
     tcp_recvspace       655360
ADSM Server
     MoveBatchSize  1000
     MoveSizeThresh           500
     TxnGroupMax              256
     UseLargeBuffers          Yes
     TCPBufsize               16384
     TCPWindowsize            0
     TCPNoDelay               Yes
ADSM Client
     TCPBuffsize         32
     TCPWindowsize       640
     txnbyte                  25600
     tcpnodelay               Y
     uselargebuffers     yes



Thanks for the help.  Alex