My first guess is you are crossing a 1GB or slower link.  Is the DWDM 
aggregating multiple links to the get the 2.5GB?  If it is your data may only 
be flowing down 1 link at whatever speed that link is running.
Also, I think a 2Gb/sec connection is closer to 200MB/sec.

Andy Huebner

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Meuleman, Ruud
Sent: Wednesday, February 10, 2010 9:43 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] Tapedrive 3592 E06 speed of 160MB/sec

Hi,

In our TSM environment we use two locations that are about 30 km away
from each other. On both sides we use TSM servers and 3592 tapedrives.
We use SAN and DWDM between the two locations. Writing data from a TSM
server to a tapelibrary that are on the same location have the speed
according the technical specifications. A TSM server writing to the
other location has not half of the speed.

For example:
On one side we have 3592 E06 tapedrives, that can write with a speed of
160MB/sec, when the TSM server is on the same location. There is 1 SAN
switch between the server and tapelibrary.
A TSM server on the other location, that is also connected with that
library, get a speed of 60MB/sec. There is a SAN switch and a DWDM
switch on one location and also a DWDM switch and a SAN switch on the
other location between the server and tapelibrary.

The speed of the HBA's in the TSM servers is 2Gb/sec, the speed of the
ports on the SAN switches are 2 Gb/sec and 4 Gb/sec and the speed of the
DWDM swiches is 2,5 Gb/sec. 2Gb/sec is about 320MB/sec. So the
bottleneck is should be 320MB/sec. When there is no other traffic on
this network, the speed should be more than 60MB/sec. The speed is of
the tests is determined of data of the  summary table of the TSM
datebase.

Can some explain why the speed is very slow? (only 60MB/sec instead of
160MB/sec). Does anyone know how one can determine the speed of DWDM
switches?

Thanks,
Ruud Meuleman

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