*BSD News Article 51319


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Newsgroups: comp.unix.bsd.freebsd.misc
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From: cracauer@wavehh.hanse.de (Martin Cracauer)
Subject: Re: SCSI - throughput
Message-ID: <1995Sep21.090850.12239@wavehh.hanse.de>
Organization: The Internet
References: <43bufs$ekb@nx2.hrz.uni-dortmund.de>
Date: Thu, 21 Sep 95 09:08:50 GMT
Lines: 65

ab@distler.maschinenbau.uni-dortmund.de (Andreas Braukmann (NetAdmin)) writes:

>hardware:    i486DX2, 66MHz, 32 MB RAM
>             EISA (sis), AHA2742AT,
>             sd0: FUJITSU M2694ES-512 812A
>             sd1: IBM OEM DFHSS4F 4040 (DHFS 34320 4.3 GB)
>os:          FreeBSD 2.0.5 (950622-SNAP)

>for the DFHS:
>bonnie -s 512
>File './Bonnie.295', size 536870912
>[...]
>    -------Sequential Output-------- ---Sequential Input-- --Random--
>    -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
>    K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
>     1379 98.3  3244 64.0 1448  47.9 1342  98.4 3226  52.3  74.7 9.1 
> 
>for the M2694:
>bonnie -s 96
>File './Bonnie.385' size: 100663296
>[...]
>    -------Sequential Output-------- ---Sequential Input-- --Random--
>    -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
>    K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
>     1367 97.5  1855 28.8   998 34.1  1339 98.1  2669 42.6  57.7 6.8


>hmm, it seems, that the character i/o is constrained by the cpu.
>I've switched from an AHA1742A to the 2742AT a couple of months ago. 
>Unfortunetly I have no exact 1742 based bonnie results for comparison, but
>as far as I remember the 1742A(driver) gave better character i/o throughput,
>especially it didn't eat that much cpu-cycles.

>Have a look at the iozone-results.
>(Same machine, 16MB RAM, disk is the Fuji. 2694)

>1742:  1973790 bytes/second for writing
>       2966137 bytes/second for reading
>time: 0.5 u  21.9 s  0:28.72 78,3%

>2742:  1760232 bytes/second for writing
>       2542905 bytes/second for reading
>time: 0.6 u  29.7 s  0:32.52  93,3%

>Should I switch back to the 1742? As I need the two SCSI-channels, I would
>have to find a second 1742, ... and that does'nt seem to be that easy these 
>days ...

If you find the difference between the iozone numbers for the 1742 and
2742 significant for your needs, maybe you should consider buying a
PCI-based 486 board. You should get about 5 MB/sec from your IBM 4.3
GB using an NCR controller, so your EISA equipment seems to limit it
anyway.

As you need more than one SCSI bus, I think an ASUS SP3G Mainboard
(with one onboard NCR) and an additional SC-200 (NCR card) may be
cheaper than buying two 1742, as you can reuse your CPU chip. Make
sure the SP3G really has a decent enough PCI implementation to run a
second NCR controller, many older PCI boards have not.

Martin
-- 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Martin Cracauer <cracauer@wavehh.hanse.de>. No NeXTMail, please.
 Norderstedt/Hamburg, Germany. Fax +49 40 522 85 36. This is a 
 private address. At (netless) work programming in data analysis.