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Date:      Wed, 16 Aug 1995 01:23:35 -0700 (PDT)
From:      "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com>
To:        msmith@atrad.adelaide.edu.au (Michael Smith)
Cc:        hardware@freebsd.org
Subject:   Re: NCR or Adaptec?
Message-ID:  <199508160823.BAA18985@gndrsh.aac.dev.com>
In-Reply-To: <199508160807.RAA28115@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Aug 16, 95 05:37:24 pm

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> 
> I'm in the process of speccing up my new PCI wonderbox, and I'm 
> looking for commentary on the relative merits of NCR 53C810 vs. Adaptec
> 2940 when it comes to PCI SCSI controllers.

My benchmarks on running ``make world'' on the exact same system, only
chang being swapping an ASUS SC-200 for an adaptec 2940 showed a 10 minute
delta in favor of the adaptec on a 3 hour 27 minute run time.

This machine is an ASUS PCI/I-P54TP4XE with 256k of 8ns PBurst cache,
A80502-100 SX963 CPU, 32MB of 60nS memory, Compex ENET-32PCI ethernet,
DEC/Quantum DSP3053L disk drive.

> 
> The particular NCR card I'm being quoted on is the ASUS PCI SC200.

Hope your not paying too much down in .au land for this stuff!

> I'll be talking to a 4G Seagate Hawk (ST15230N) and a Sony CDU76S
> with it initially, and probably an Exabyte EXB8200.

Given you are talking to a single disk drive, I doubt that the
AHA2940 is worth the $300.00.  The place this controller starts to
pull away seriously from the NCR card is in either 3 or more disks
on 1 controller, or 3 or more controllers on the PCI bus.

I do not have good data on multiple controller aha2940 setups, but I
do know that the NCR rolls off in total bandwidth at 3 or more drives
on a single bus, or more than 3 controllers doing concurrent access.

This occurs before CPU cycle saturation, so it is not a CPU bottleneck.

> Any comments?  If the Adaptec is worth the extra $300 or so, I'll bite.

IMHO, not for a single user or single disk system, you'll never create
the I/O load to use the advanced features of the aha2940, and thus
save the $300 and spend it else where.

-- 
Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
Accurate Automation Company                 Reliable computers for FreeBSD



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