From: Stan Hoeppner <stan@hardwarefreak.com>
To: Roy Sigurd Karlsbakk <roy@karlsbakk.net>
Cc: Chris Murphy <lists@colorremedies.com>,
linux-raid Raid <linux-raid@vger.kernel.org>
Subject: Re: recommended way to add ssd cache to mdraid array
Date: Sat, 12 Jan 2013 08:14:04 -0600 [thread overview]
Message-ID: <50F16FAC.7000509@hardwarefreak.com> (raw)
In-Reply-To: <2258826.8.1357992379424.JavaMail.root@zimbra>
On 1/12/2013 6:06 AM, Roy Sigurd Karlsbakk wrote:
>> Unlikely to make up the difference is the scheduler. Parallel fs's
>> like XFS don't perform nearly as well with CFQ, so you should have a
>> kernel parameter elevator=noop.
>
> uh… how can the filesystem chosen be relevant to the disk elevator?
It's the other way round. The chosen elevator can cause problems with
the filesystem. You should find this relevant conversation amongst the
lead XFS developers educational:
http://oss.sgi.com/archives/xfs/2011-07/msg00464.html
> CFQ will try to optimize access to reduce seeks
"Completely Fair Queuing" -- The name alone tells you how it works. It
most certainly does not do what you state. Please read the brief
Wikipedia article: http://en.wikipedia.org/wiki/CFQ
> and should be completely independent on the filesystem used on top.
Operative word: "should"
The USA should not be $16 Trillion in debt, but it is. By international
law whales should not be killed, but they still are. Etc.
--
Stan
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next prev parent reply other threads:[~2013-01-12 14:14 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-22 6:57 recommended way to add ssd cache to mdraid array Thomas Fjellstrom
2012-12-23 3:44 ` Thomas Fjellstrom
2013-01-09 18:41 ` Thomas Fjellstrom
2013-01-10 6:25 ` Chris Murphy
2013-01-10 10:49 ` Thomas Fjellstrom
2013-01-10 21:36 ` Chris Murphy
2013-01-11 0:18 ` Stan Hoeppner
2013-01-11 12:35 ` Thomas Fjellstrom
2013-01-11 12:48 ` Thomas Fjellstrom
2013-01-14 0:05 ` Tommy Apel Hansen
2013-01-14 8:58 ` Thomas Fjellstrom
2013-01-14 18:22 ` Thomas Fjellstrom
2013-01-14 19:45 ` Stan Hoeppner
2013-01-14 21:53 ` Thomas Fjellstrom
2013-01-14 22:51 ` Chris Murphy
2013-01-15 3:25 ` Thomas Fjellstrom
2013-01-15 1:50 ` Stan Hoeppner
2013-01-15 3:52 ` Thomas Fjellstrom
2013-01-15 8:38 ` Stan Hoeppner
2013-01-15 9:02 ` Tommy Apel
2013-01-15 11:19 ` Stan Hoeppner
2013-01-15 10:47 ` Tommy Apel
2013-01-16 5:31 ` Thomas Fjellstrom
2013-01-16 8:59 ` John Robinson
2013-01-16 21:29 ` Stan Hoeppner
2013-02-10 6:59 ` Thomas Fjellstrom
2013-01-16 22:06 ` Stan Hoeppner
2013-01-14 21:38 ` Tommy Apel Hansen
2013-01-14 21:47 ` Tommy Apel Hansen
2013-01-11 12:20 ` Thomas Fjellstrom
2013-01-11 17:39 ` Chris Murphy
2013-01-11 17:46 ` Chris Murphy
2013-01-11 18:52 ` Thomas Fjellstrom
2013-01-12 0:47 ` Phil Turmel
2013-01-12 3:56 ` Chris Murphy
2013-01-13 22:13 ` Phil Turmel
2013-01-13 23:20 ` Chris Murphy
2013-01-14 0:23 ` Phil Turmel
2013-01-14 3:58 ` Chris Murphy
2013-01-14 22:00 ` Thomas Fjellstrom
2013-01-11 18:51 ` Thomas Fjellstrom
2013-01-11 22:17 ` Stan Hoeppner
2013-01-12 2:44 ` Thomas Fjellstrom
2013-01-12 8:33 ` Stan Hoeppner
2013-01-12 14:44 ` Thomas Fjellstrom
2013-01-13 19:18 ` Chris Murphy
2013-01-14 9:06 ` Thomas Fjellstrom
2013-01-11 18:50 ` Stan Hoeppner
2013-01-12 2:45 ` Thomas Fjellstrom
2013-01-12 12:06 ` Roy Sigurd Karlsbakk
2013-01-12 14:14 ` Stan Hoeppner [this message]
2013-01-12 16:37 ` Roy Sigurd Karlsbakk
2013-01-10 13:13 ` Brad Campbell
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