From: Martin Wilck <mwilck@arcor.de>
To: stan@hardwarefreak.com
Cc: Peter Landmann <sfrazt@googlemail.com>, linux-raid@vger.kernel.org
Subject: Re: RAID 5 doesn't scale
Date: Wed, 03 Apr 2013 20:23:47 +0200 [thread overview]
Message-ID: <515C73B3.5060704@arcor.de> (raw)
In-Reply-To: <515C2C3C.3020400@hardwarefreak.com>
On 04/03/2013 03:18 PM, Stan Hoeppner wrote:
> You didn't mention your stripe_cache_size value. It'll make a lot of
> difference. Make sure it's at least 4096. The default is 256.
I'm not getting it - why would stripe cache size matter in a random
read/write test? If the disks are large enough and the pattern is really
random, the cache should hardly ever be hit (s_c_z = 4096 =^ 16MB cache
per disk, that's 0.01% of disk size for a 160GB SSD).
I read that Peter confirmed the influence of stripe_cache_size, but I'd
like to understand why it matters in this case.
Martin
next prev parent reply other threads:[~2013-04-03 18:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-03 11:00 RAID 5 doesn't scale Peter Landmann
2013-04-03 11:21 ` Benjamin ESTRABAUD
2013-04-03 18:34 ` Martin Wilck
2013-04-03 20:38 ` Peter Landmann
2013-04-04 13:40 ` Benjamin ESTRABAUD
2013-04-03 13:18 ` Stan Hoeppner
2013-04-03 15:23 ` keld
2013-04-03 15:31 ` Peter Landmann
2013-04-03 18:35 ` Stan Hoeppner
2013-04-03 18:23 ` Martin Wilck [this message]
2013-04-03 20:36 ` Peter Landmann
2013-04-03 21:19 ` Peter Landmann
2013-04-03 21:24 ` Stan Hoeppner
2013-04-03 21:29 ` Peter Landmann
2013-04-03 21:15 ` Stan Hoeppner
2013-04-03 19:56 ` Roy Sigurd Karlsbakk
2013-04-03 21:12 ` Peter Landmann
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