[1694] in linux-scsi channel archive
Re: TCP/IP over SCSI
daemon@ATHENA.MIT.EDU (Stephen E. Shipman)
Wed Apr 9 18:50:48 1997
Date: Wed, 9 Apr 1997 18:04:05 -0500 (EST)
From: "Stephen E. Shipman" <seshipma@wixer.syrinx.org>
To: yuri mironoff <yuri@rgti.com>
Cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <Pine.A41.3.95.970409134438.76616B-100000@bdmg30.rgti.com>
On Wed, 9 Apr 1997, yuri mironoff wrote:
> Max TCP bandwidth seems to be around 430 KB/sec. I may be missing
> something but isnt that SLOWER than 10BASE-T???
>
> Can someone possibly comment on the throughput - or lack thereof?
> Is it possible that one of the two cards used in the benchmark
> (the Adaptec 1520) slows it down that much?
I'll take a shot at it -- The 1520 is not exatcly a seed deamon of a
SCSI card. If it's an original AHA1520 then it's a SCSI 1 device with a
max transfer rate of 5Mbps on an 8 bit bus...something you're not likely
to see given the card's reputation as a pokey, low-cost, 16bit ISA
controller.
As for the throughput vs. 10Base-T, your 430KBps works out to around
3.5Mbps -- which is what Ethernet will give you when it's running at
"best" efficiency (approximately 30% utilization; at higher levels of
utilization the channel access method {CSMA/CD} starts eating up bandwidth
with overhead). So, you're on a par with Ethernet.
Faster SCSI cards might help push this number higher (better ISA cards,
fast SCSI-2, etc)... You don't say what size your data frames are; larger
frames would probably equate to higher throughput, at least on large I/Os.
For what it's worth,
-- Stephen
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