high speed drives

[Bill Heiser]

In article <797 at tiamat.fsc.com> jim at tiamat.fsc.com ( IT Manager) writes:
>> 
>> from "time dd if=/dev/XXXX of=/dev/null bs=100k count=10"
>> 
>> for the Miniscribe 3180S
>> 10+0 records in
>> 10+0 records out
>> 
>> real        17.7
>> user         0.0
>> sys          0.4
>
>under Unix:
>real        3.0
>user        0.0
>sys         0.2
>
>From the looks of those numbers, it seems that the data you have on the
>drive (or how it is arranged) can have something to do with the performance
>under this type of test.

This is interesting.  I tried reading several different partitions 
(/dev/dsk/0s0, /dev/dsk/0s1, /dev/dsk/0s3, etc), and all came out about
like this:

Script started on Fri Feb 22 17:49:25 1991
# sh
# time dd if=/dev/dsk/0s3 of=/dev/null bs=100k count=10
10+0 records in
10+0 records out

real        7.6
user        0.0
sys         1.5
# # 
script done on Fri Feb 22 17:49:47 1991

This is on a 386/25 running Esix-D.  /dev/dsk/0s3 is my /usr partition
(where about 100mb worth of Usenet News is sitting).  The disk is
a CDC Wren IV (94171-307).

Your "real time" numbers seemed to vary from 3.0 to 8.0 -- Mine
seemed to stay about the same.  Maybe system loading, different buffer
cache size, or some other factor?

Bill


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