Re: SCSI write caching (was: Dumb question: Which is "better" SCSI or IDE disks?)

C S Hendrix (shendrix@escape.widomaker.com)
Wed, 09 Dec 1998 12:20:18 -0500


In message <5ln24ye208.fsf@tequila.cs.yale.edu>, Stefan Monnier writes:

> >>>>> "Christopher" == Christopher Smith <cbsmith@envise.com> writes:
> > In general, I'd say, unless you know you need write caching disabled, you
> > probably should have it enabled.
>
> Beside the `is it safe', I believe the main question is:
> how much performance improvement can I expect (this will of course depend on
> the load, but then I'd like to know about that too) ?

Last night I ran some tests with bonnie.c on my system with a DPT
2044 controller and two Seagate Hawk fast-wide drives.

The tests were actually faster with write cache turned off. I'm not
sure I really expected it to be faster, but I was surprised that
cache slowed things down.

I'm talking too about a fairly significant different of nearly
2MB/sec on the block output test.

Granted, bonnie and other benchmarks are not the best, but I think
it is safe to at least say write-cache enabled was slower.

--
Shannon - shendrix@widomaker.com - InfiNet?
----------------------------------------------------------------------
"We are all of us in the gutter, some of us looking at the stars." --
Alexander Pope

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