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From: lphillips@lpami.wimsey.bc.ca (Larry Phillips)
Newsgroups: comp.sys.amiga
Subject: Re: DiskPerf results
Message-ID: <2398@van-bc.UUCP>
Date: 3 May 89 13:40:13 GMT
Sender: root@van-bc.UUCP
Lines: 52


In <7965@killer.Dallas.TX.US>, elg@killer.Dallas.TX.US (Eric Green) writes:
>In message <21149@srcsip.UUCP>, carpent@coltrane.SRC.Honeywell.COM (Todd Carpenter) says:
>>In case you folks are interested, I ran DiskPerf on my beastie:
>>A2090a
>>A2620
>>Rodime SCSI HD.  Basically, it is their 180MB 5 1/4" SCSI drive, with a few
>>       hand modifications.  Like, 12msec access, 12MHz transfer.  Hee-hee.
>>r/w speed:	    buf 32768 bytes, rd 635500 byte/sec, wr 372275 byte/sec
>>r/w speed:	    buf 131072 bytes, rd 655360 byte/sec, wr 427990 byte/sec
>>r/w speed:	    buf 524288 bytes, rd 699050 byte/sec, wr 455902 byte/sec
>>Unfortunately, I was surprised the numbers were so low.  I had hoped for
>>significantly higher. Anyone have any suggestions?  Or are these fast for Amiga
>>drives?

>I suspect that the limiting factors are a) the file system, and b) the
>A2090A. I got about the same results from a 2090A and a Quantum 80S.
>The 2090A limits speed because it is limited to the old 1mb/sec
>asynchronous SCSI protocol (meaning that however hot your drive is,

Async SCSI specs 1.25 Mbytes/second

>it's limited to 1mb/sec max throughput). However, someone else got

Andy Finkel tells me he got 1.2 MBytes/second from a CDC Wren V (or possibly a
VI), sometime not long after I told him about the 875K/sec from a Wren IV
(empty 50 meg partition).

>basically the same numbers from a Quantum 80s and a Microbotics
>Hardframe (which has the new 5mb/sec synchronous SCSI, i.e., will take

Well, they will have it anyway. I called them last week, and it does not yet
support synchronous SCSI

>data as fast as the Quantum can dish it out, 4mb/sec). So I have to
>conclude that file system overhead has something to do with it,
>too....

I'm sure it does. The 875K/sec dropped off to about 690K/sec after purring some
files on the drive. Diskperf is also quite sensitive to what else is running,
and to exactly what the bitmap looks like when you run it.

-larry

--
Frisbeetarianism: The belief that when you die, your soul goes up on
                  the roof and gets stuck.
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|   //   Larry Phillips                                                |
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|        COMPUSERVE: 76703,4322                                        |
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