From: Roman Mamedov <rm@romanrm.ru>
To: NeilBrown <neilb@suse.de>
Cc: Kasper Sandberg <kontakt@sandberg-consult.dk>,
linux-raid@vger.kernel.org
Subject: Re: raid6 low performance 8x3tb drives in singledegraded mode(=7x3tb)
Date: Wed, 19 Sep 2012 13:40:30 +0600 [thread overview]
Message-ID: <20120919134030.222e4b04@natsu> (raw)
In-Reply-To: <20120919162557.03df6af2@notabene.brown>
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On Wed, 19 Sep 2012 16:25:57 +1000
NeilBrown <neilb@suse.de> wrote:
> RAID5/RAID6 write speed is never going to be brilliant, but there probably is
> room for improvement. Hopefully one day I figure out how to effect that
> improvement.
"/sys/block/md*/md/stripe_cache_size" is absolutely the first thing one should
look at when facing a problem with md RAID5/6 write performance. It is
understandable that the default value can't be high (as it consumes a lot of
RAM on large disk counts), but increasing it if you have the RAM can increase
the write speed by 200 to 400%:
http://peterkieser.com/2009/11/29/raid-mdraid-stripe_cache_size-vs-write-transfer/
--
With respect,
Roman
~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Stallman had a printer,
with code he could not see.
So he began to tinker,
and set the software free."
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next prev parent reply other threads:[~2012-09-19 7:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-12 0:03 raid6 low performance 8x3tb drives in singledegraded mode(=7x3tb) Kasper Sandberg
2012-09-12 9:42 ` Peter Grandi
2012-09-12 13:38 ` Peter Grandi
2012-09-19 6:25 ` NeilBrown
2012-09-19 7:40 ` Roman Mamedov [this message]
2012-09-19 16:31 ` Stan Hoeppner
2012-09-20 0:26 ` Kasper Sandberg
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