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Date:      Wed, 9 May 2001 23:58:33 -0500
From:      "Scott Mace" <smace@intt.org>
To:        "Greg Lehey" <grog@lemis.com>
Cc:        "Dan Phoenix" <dphoenix@bravenet.com>, "FreeBSD Questions" <questions@FreeBSD.ORG>
Subject:   RE: vinum on 2 ide drives?
Message-ID:  <BFENLHFJOCHGGGAHGHOPGEAECCAA.smace@intt.org>
In-Reply-To: <20010510133425.K56501@wantadilla.lemis.com>

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Absolutely, this is not a direct comparison.


My results were on an BX chipset with the normal intel ATA33
chip.  The MB has an on-board promise ATA100 chip (ASUS CUBX-E)
but the system was very flakey, random filesystem corruption
with no kernel error messages (yeah).  I tried several combinations
to see if I could get better performance on the ATA33.
These were with IBM DLTA-307030 drives.

When I started I was getting about 10MB/sec write 20MB/sec read on a single
drive.

I enabled tagged queueing on the drive.  This sent the performance
to ~20MB/sec write 21MB/sec read.  After intensive cvsup + cvs co +
tars, I got kernel error messages about tag error and timeouts.

I turned off tagged queueing and turned on write caching.  I got
~20MB/sec write ~20MB/sec read, so I was happy.  This was all on
single drives (no vinum).

I then decided to mirror a filesystem.  write performance was almost
exactly 50% slower.  Without write-cache I got 3MB/sec write (yeah!!).

I tried putting each drive on a seperate bus, no change.  The current
setup is one drive master the other slave on the same bus.

I've used vinum for a while on wide scsi and u2wide scsi with none of these
problems.  As long as the bus isn't congested, a mirror isn't any slower
than
a single drive and a stripe+concat is typically much faster than a single
drive,
and you can always just add another bus to stop the congestion problems...

Sequential I/O tests are not a real-world, but is does give you an
idea of whether or not things are working right.

	Scott

> -----Original Message-----
> From: Greg Lehey [mailto:grog@lemis.com]
> Sent: Wednesday, May 09, 2001 11:04 PM
> To: Scott Mace
> Cc: Dan Phoenix; FreeBSD Questions
> Subject: Re: vinum on 2 ide drives?
>
>
>
> It's difficult to guess what's going on here.  Looking at your
> configuration below, I'd guess that you're not comparing things
> directly.
>
> > drive vinumdrive0 device /dev/ad0s1e
> > drive vinumdrive2 device /dev/ad0s1f
> > drive vinumdrive4 device /dev/ad0s1g
> > drive vinumdrive1 device /dev/ad1s1e
> > drive vinumdrive3 device /dev/ad1s1f
> > drive vinumdrive5 device /dev/ad1s1g
>
> These are four drives too many.  You don't want more than one drive
> per spindle.
>
> Greg
> --
> Finger grog@lemis.com for PGP public key
> See complete headers for address and phone numbers
>
>
>


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