[Veritas-bu] max throughput of 20 Mbit per sec to tape ...

Unfortuniately the 'standard' doesn't always function as planned or
hoped.  We are still realizing better throughput thru not negotiating
and by tweaking the buffers.  If wanted, we can supply the numbers we
found helpful.

Thank you,
 
 
Samuel J. Coco, STG
Functional Area Manager, ARL
Sr UNIX Administrator
BELL      301 394-1151 DSN 290
CELL (B) 240 398-7121 / (H)443 496-1623
HOME     410 604-2415
Email  scoco AT arl.army DOT mil


-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of Jim
Horalek
Sent: Wednesday, June 30, 2004 11:35 AM
To: 'William Enestvedt'; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] max throughput of 20 Mbit per sec to tape ...


My understanding is auto-negotiation wasn't in the 10/100 specs so is
was poorly implemented. It is part of spec for GigE. Most GigE do 10/100
as well so I guess we have some kind of standard now.

jim

-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of William
Enestvedt
Sent: Wednesday, June 30, 2004 5:58 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] max throughput of 20 Mbit per sec to tape ...


I saw Samuel Coco's suggestion to Rob DeLanghe to consider his SUn's
network link, and the advice not to auto-negotiate.
   I would like to point out that, while this has always been my
experience on Suns, too, recently I have heard from Sun support staff
that the newer ethernet controllers (e.g., dmfe) are "better" and should
be allowed to autonegotiate.
   Of course, any failures are still due to the switch. (Naturally.) And
when I remind the phone guys about Sun's old position of "only suckers
autonegotiate" and how it's still all over their InfoDocs and support
site, I can hear feet shifting under the chair and a lot of
throat-clearing. :7)
   I snorted derisively the first time they told me this -- but I have
recently experienced a rash of half a dozen different Sun Fire V100s
whose dmfe NICs have dropped to half-duplex despite being forced at the
switch and via the /platform/(I_forget)/kernel/drv/dmfe.conf file. Since
setting one to autonegotiate, its problem has gone. [Last night, though,
on a freshly-patched V100 running Solaris 8, the dmfe dropped to
half-duplex the very second the NBU job kicked off!]
    So, I, too, am reconsidering the old received wisdom of never
autonegotiating, and experimenting with it. -wde P.S. Rob, play with the
buffer sizes before you do anythying else. Search the Media Server's
logs for messages about waiting for an empty or a full buffer, and
you'll know which way to go. A 280R should be able to keep up with an
L25: I have a li'l V120 driving an L25 with a single SDLT 220 drive in
it, and I usually get a good 10 Mb.
--
Will Enestvedt
UNIX System Administrator
Johnson & Wales University -- Providence, RI

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