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Tuning Network to utilize Jumbo Frames on Gig-Eth ernet.
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Post Tuning Network to utilize Jumbo Frames on Gig-Eth ernet. 
Hi David

NetWorker does not have any knobs to control Ethernet settings; you =
have to
do this outside of NetWorker. If you do use jumbo frames, make sure =
that
EVERYTHING in the path between the NetWorker client and the NetWorker
storage node is jumbo frame-capable; otherwise, you'll have even worse
performance than if you weren't using jumbo frames.

If you are using Intel Ethernet adapters, see
http://www.intel.com/network/connectivity/resources/doc_library/tech_bri=
ef/K
ey_Performance_Gig.pdf. This white paper makes the case that Intel's =
TCP
Segmentation (aka "Large Send Off-load") technology is better than =
jumbo
frames. How does it work? "It reduces the OS burden involved in =
processing
large files into packets by off-loading this task onto hardware using
specialized silicon on the adapter."

Some Ethernet adapters have TCP offload engines (TOE) onboard, which =
remove
the very substantial IP processing burden from the host CPU. TOEs are =
more
expensive than regular Ethernet adapters (and they should be, for what =
they
provide).

So, the Intel Gigabit Ethernet adapter gives you some of the benefit of =
a
TOE (e.g., some network operations done by the adapter, instead of the =
host
CPU), without the extra cost. TCP Segmentation doesn't do the =
functions of
a TOE, of course; but it may provide some of the benefits (decreased =
CPU
load) in your environment.

Look for features like this in other vendor's products. I knew the =
Intel
one, so used it as an illustration here.

Hope this helps.

tl

Terry Lemons
CLARiiON Applications Integration Engineering
EMC=B2 =20
where information lives
=20
4400 Computer Drive, MS D239
Westboro MA 01580
Phone: 508 898 7312
Email: Lemons_Terry < at > emc.com



-----Original Message-----
From: Legato NetWorker discussion =
[mailto:NETWORKER < at > LISTMAIL.TEMPLE.EDU] On
Behalf Of Fields, David
Sent: Wednesday, December 15, 2004 3:12 PM
To: NETWORKER < at > LISTMAIL.TEMPLE.EDU
Subject: [Networker] Tuning Network to utilize Jumbo Frames on =
Gig-Ethernet.

I haven't been able to find any information in the NetWorker =
documentation
this subject, so I thought I would ask here. Does NetWorker =
automatically
adjust itself to utilize jumbo frames on a gig Ethernet network, or do =
you
have to tune it somehow to make use out of it? Also, I've heard it
mentioned a few times on there that you should tune your Ethernet frame =
size
to your tape frame size to get the best throughput. Can any one =
confirm
this or provide any guidelines?

Thanks in advance.

David Fields
Network Specialist
ACS Government Systems
Phone: (859) 277-8800 x231
david.fields < at > acs-inc.com

Note: To sign off this list, send a "signoff networker" command via =
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Note: To sign off this list, send a "signoff networker" command via email
should be sent to stan < at > temple.edu
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