From: Alasdair G Kergon <agk@redhat.com>
To: Mike Snitzer <snitzer@redhat.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Heinz Mauelshagen <heinzm@redhat.com>,
linux-kernel@vger.kernel.org,
device-mapper development <dm-devel@redhat.com>,
Mikulas Patocka <mpatocka@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Joe Thornber <ejt@redhat.com>
Subject: Re: [dm-devel] dm: dm-cache fails to write the cache device in writethrough mode
Date: Sat, 23 Mar 2013 03:48:03 +0000 [thread overview]
Message-ID: <20130323034803.GB30269@agk-dp.fab.redhat.com> (raw)
In-Reply-To: <20130323032715.GA7692@redhat.com>
On Fri, Mar 22, 2013 at 11:27:16PM -0400, Mike Snitzer wrote:
> So the big difference is the thinp-test-suite uses intermediate linear
> DM layers above the slower sd device (spindle/data) -- whereas in your
> setup the origin device is direct to sd (8:0).
I would think the difference is because DM issues (edited) copies of
incoming bios to the layers underneath, so changes don't propagate back
up.
Darrick: if you retest with a dm linear device, does the problem go
away?
Alasdair
next prev parent reply other threads:[~2013-03-23 3:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-22 20:11 [PATCH] " Darrick J. Wong
2013-03-22 20:21 ` Ben Hutchings
2013-03-22 20:50 ` Darrick J. Wong
2013-03-22 21:35 ` Mike Snitzer
2013-03-22 22:34 ` Mike Snitzer
2013-03-22 23:16 ` [dm-devel] " Darrick J. Wong
2013-03-23 3:27 ` Mike Snitzer
2013-03-23 3:48 ` Alasdair G Kergon [this message]
2013-03-23 5:15 ` [dm-devel] " Darrick J. Wong
2013-03-23 21:08 ` Mike Snitzer
2013-03-23 22:56 ` Mike Snitzer
2013-03-25 23:59 ` [PATCH v2] dm cache: fix writes to " Mike Snitzer
2013-03-23 21:13 ` [dm-devel] dm: dm-cache fails to write the " Alasdair G Kergon
2013-03-23 3:00 ` [dm-devel] [PATCH] " Alasdair G Kergon
2013-03-25 10:28 ` Joe Thornber
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