John,

First of all I didn't ask the question, this is:

>         Andres j. Ogayar
>         Data processing Dept.
>         HUGHES M.E.E.
>         Malaga, Spain

Second: We didn't had any los of cpu power at all and this system works still (in my knowlefge) with fl. I think that you had a different problem.

Greetings,

André     \\//
----------
From:   [log in to unmask]
Sent:   donderdag 16 oktober 1997 20:40
To:     [log in to unmask]
Subject:        Re: Re[2]: Mirror hard disks on a 937?

Hi Andre,

In answer to your question ...

>      John,
>
>         Thanks for your answer! I am asking now my HP representative in
>      order to see the costs involved.
>
>         The main question: Did you notice preformance degradation due to
>      the mirror? As you will know, the 937 is a little machine, and since
>      it is our main production machine, we have to balance carefully the
>      advantages/performance penalties.
>
>         Thanks again,
>
>         Andres
>
We had in fact a very servere i/o bottleneck, caused by the old fl
raid drives of 4 -8 gb which we were using  (we coulnd never get more than 75% cpu
utilization). We replaced these with a large number of 2 gb
mirrored SCSI drives and were able to reach 100% cpu easly, in fact
almost immediatly.  I monitor our systems pretty closly but because
of the way mirror/ix works with the OS it's hard to get any hard
figures, but I would guess that the perfomance hit is probably
between 5 - 10 % and probably closer to 5%. I would guess that if the
mirroring caused enough of a perfomance problem to be noticable to
your users, you  probably had an upgrade in your near future anyway.
Hope this helps.

John "Danger" Skelton