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From: Andy Smith <andy@strugglers.net>
To: linux-raid@vger.kernel.org
Subject: Re: Can extremely high load cause disks to be kicked?
Date: Fri, 1 Jun 2012 19:25:24 +0000	[thread overview]
Message-ID: <20120601192524.GH3867@bitfolk.com> (raw)
In-Reply-To: <4FC81B85.8090807@hardwarefreak.com>

Hi Stan,

On Thu, May 31, 2012 at 08:31:49PM -0500, Stan Hoeppner wrote:
> On 5/31/2012 3:31 AM, Andy Smith wrote:
> > Now, is this sort of behaviour expected when under incredible load?
> > Or is it indicative of a bug somewhere in kernel, mpt driver, or
> > even flaky SAS controller/disks?
> 
> It is expected that people know what RAID is and how it is supposed to
> be used.  RAID is to be used for protecting data in the event of a disk
> failure and secondarily to increase performance.  That is not how you
> seem to be using RAID.

Just to clarify, this was the hypervisor host. The VMs on it don't
use RAID themselves as that would indeed be silly.

> There are a number of scenarios where md RAID is better than hardware
> RAID and vice versa.  Yours is a case where hardware RAID is superior,
> as no matter the host CPU load, drives won't get kicked offline as a
> result, as they're under the control of a dedicated IO processor (same
> for SAN RAID).

Fair enough, thanks.

Cheers,
Andy

  parent reply	other threads:[~2012-06-01 19:25 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-31  8:31 Can extremely high load cause disks to be kicked? Andy Smith
2012-06-01  1:31 ` Stan Hoeppner
2012-06-01  3:15   ` Igor M Podlesny
2012-06-01 14:12     ` Stan Hoeppner
2012-06-01 15:19       ` Igor M Podlesny
2012-06-02  4:45         ` Stan Hoeppner
2012-06-02  7:57           ` Igor M Podlesny
2012-06-02  9:16             ` Stan Hoeppner
2012-06-01 19:25   ` Andy Smith [this message]
2012-06-02  5:47     ` Stan Hoeppner
2012-06-03  3:30       ` Andy Smith
2012-06-03  4:05         ` Igor M Podlesny
2012-06-03 22:05           ` Andy Smith
2012-06-04  1:55             ` Stan Hoeppner
2012-06-04  9:06               ` Igor M Podlesny
2012-06-03  6:49         ` Stan Hoeppner
2012-06-04  0:02           ` Andy Smith
2012-06-04  6:58             ` Stan Hoeppner
2012-06-04  4:13 ` NeilBrown

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