From: Chris Mason <mason@suse.com>
To: linux-lvm@sistina.com
Cc: Andrew Theurer <habanero@us.ibm.com>,
Kevin Corry <corryk@us.ibm.com>,
linux-kernel@vger.kernel.org
Subject: [linux-lvm] Re: [Announce] device-mapper beta3 (fast snapshots)
Date: Tue Jul 16 12:26:02 2002 [thread overview]
Message-ID: <1026840444.21656.544.camel@tiny> (raw)
In-Reply-To: <20020716163157.GA11334@fib011235813.fsnet.co.uk>
On Tue, 2002-07-16 at 12:31, Joe Thornber wrote:
> > Joe, are you absolutely sure these tests had the disk cache disabled? That's
> > the only hardware thing I can think of that would make a difference.
>
> Absolutely sure. Those figures were for a pair of PVs that were
> sharing an IDE cable so I can certainly get things moving faster.
Some IDE drives ignore commands to turn off the write back cache, or
turn it back on when load gets high.
Try iozone -s 50M -i 0 -o with writeback on and off. If you get the
same answer the benchmarks are suspect....
-chris
WARNING: multiple messages have this Message-ID (diff)
From: Chris Mason <mason@suse.com>
To: linux-lvm@sistina.com
Cc: Andrew Theurer <habanero@us.ibm.com>,
Kevin Corry <corryk@us.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [Announce] device-mapper beta3 (fast snapshots)
Date: 16 Jul 2002 13:27:24 -0400 [thread overview]
Message-ID: <1026840444.21656.544.camel@tiny> (raw)
In-Reply-To: <20020716163157.GA11334@fib011235813.fsnet.co.uk>
On Tue, 2002-07-16 at 12:31, Joe Thornber wrote:
> > Joe, are you absolutely sure these tests had the disk cache disabled? That's
> > the only hardware thing I can think of that would make a difference.
>
> Absolutely sure. Those figures were for a pair of PVs that were
> sharing an IDE cable so I can certainly get things moving faster.
Some IDE drives ignore commands to turn off the write back cache, or
turn it back on when load gets high.
Try iozone -s 50M -i 0 -o with writeback on and off. If you get the
same answer the benchmarks are suspect....
-chris
next prev parent reply other threads:[~2002-07-16 12:26 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-07-12 18:26 [linux-lvm] Re: [Announce] device-mapper beta3 (fast snapshots) Andrew Theurer
2002-07-12 23:21 ` Andrew Theurer
2002-07-15 4:00 ` [linux-lvm] " Joe Thornber
2002-07-15 8:59 ` Joe Thornber
2002-07-15 9:44 ` [linux-lvm] " Andrew Theurer
2002-07-15 14:39 ` Andrew Theurer
2002-07-15 7:40 ` [linux-lvm] " Joe Thornber
2002-07-15 12:40 ` Joe Thornber
2002-07-15 14:13 ` [linux-lvm] " Kevin Corry
2002-07-15 18:56 ` Kevin Corry
2002-07-16 3:42 ` Joe Thornber
2002-07-16 8:42 ` Joe Thornber
2002-07-16 11:11 ` Andrew Theurer
2002-07-16 16:05 ` Andrew Theurer
2002-07-16 11:32 ` Joe Thornber
2002-07-16 16:31 ` Joe Thornber
2002-07-16 12:26 ` Chris Mason [this message]
2002-07-16 17:27 ` Chris Mason
2002-07-16 13:05 ` [linux-lvm] " Patrick Caulfield
2002-07-17 5:31 ` Joe Thornber
2002-07-17 10:31 ` Joe Thornber
2002-07-17 5:35 ` Alan Cox
2002-07-17 11:46 ` Alan Cox
2002-07-16 13:13 ` [linux-lvm] " James Manning
2002-07-17 6:03 ` Joe Thornber
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