From: John Robinson <john.robinson@anonymous.org.uk>
To: NeilBrown <neilb@suse.de>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Mike Snitzer <snitzer@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Alasdair G Kergon <agk@redhat.com>,
jens.axboe@oracle.com, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
linux-ide@vger.kernel.org, linux-fsdevel@vger.kernel.org,
device-mapper development <dm-devel@redhat.com>
Subject: Re: [dm-devel] REQUEST for new 'topology' metrics to be moved out of the 'queue' sysfs directory.
Date: Thu, 25 Jun 2009 12:36:15 +0100 [thread overview]
Message-ID: <4A43612F.2000100@anonymous.org.uk> (raw)
In-Reply-To: <125b48b7ffc99a496fbdd512f38cada5.squirrel@neil.brown.name>
On 25/06/2009 12:07, NeilBrown wrote:
[...]
> stripe-width is only really needed on raid4/5/6 as it is aimed at
> avoiding read-modify-write, so it would be the stripe size, which would
> be minimum_io_size.
[...]
> stride-size is used for raid0 or raid4, or the "Asymmetric" raid5 layouts.
> It allows ext3 to stagger which drive certain 'hot' data structures are
> on. The current metrics don't allow for that at all.
> I'm not saying they should, and I'm not sure how they could. But it
> is sad.
Even sadder, when a raid 0/4/5/6 is reshaped over more discs (and
probably other scenarios outwith md), both stripe-width and stride-size
change. Is there any prospect this new stacking could give us the
opportunity to tell our client (LVM, filesystem, whatever) about the
change, or that they'll be able to take advantage of it?
Cheers,
John.
next prev parent reply other threads:[~2009-06-25 11:36 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-25 3:58 REQUEST for new 'topology' metrics to be moved out of the 'queue' sysfs directory Neil Brown
2009-06-25 8:00 ` Martin K. Petersen
2009-06-25 11:07 ` [dm-devel] " NeilBrown
2009-06-25 11:36 ` John Robinson [this message]
2009-06-25 17:43 ` Martin K. Petersen
2009-06-25 12:17 ` berthiaume_wayne
2009-06-25 17:38 ` Martin K. Petersen
2009-06-25 17:46 ` Linus Torvalds
2009-06-25 19:34 ` Jens Axboe
2009-06-26 11:58 ` [dm-devel] " Neil Brown
2009-06-26 14:48 ` Martin K. Petersen
2009-07-07 1:47 ` [dm-devel] " Neil Brown
2009-07-07 5:29 ` Martin K. Petersen
2009-07-09 0:42 ` Neil Brown
2009-07-07 22:06 ` Bill Davidsen
2009-06-25 19:40 ` [dm-devel] " Jens Axboe
2009-06-26 12:41 ` Neil Brown
2009-06-26 12:50 ` Jens Axboe
2009-06-26 13:16 ` NeilBrown
2009-06-26 13:27 ` Jens Axboe
2009-06-26 13:41 ` NeilBrown
2009-06-26 13:49 ` Jens Axboe
2009-06-27 12:50 ` Neil Brown
2009-06-26 13:23 ` [dm-devel] " NeilBrown
2009-06-26 13:29 ` Jens Axboe
2009-06-27 12:32 ` Neil Brown
2009-06-29 10:18 ` [dm-devel] " Jens Axboe
2009-06-29 10:52 ` NeilBrown
2009-06-29 11:41 ` Jens Axboe
2009-06-29 12:45 ` Boaz Harrosh
2009-06-29 12:52 ` Jens Axboe
2009-06-29 23:09 ` Andreas Dilger
2009-07-01 0:29 ` Neil Brown
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