From: Stan Hoeppner <stan@hardwarefreak.com>
To: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>,
linux-raid@vger.kernel.org
Subject: Re: RAID-0/5/6 performances
Date: Fri, 06 Dec 2013 03:24:18 -0600 [thread overview]
Message-ID: <52A197C2.1090805@hardwarefreak.com> (raw)
In-Reply-To: <20131205192454.GA5695@lazy.lzy>
On 12/5/2013 1:24 PM, Piergiorgio Sartor wrote:
> The "stripe_cache_size" was set to the max 32768.
You don't want to set this so high. Doing this will:
1. Usually decrease throughput
2. Eat a huge amount of memory. With 5 drives:
((32768*4096)*5)/1048576 = 640 MB RAM consumed for the stripe buffer
For 5 or fewer pieces of spinning rust a value of 2048 or less should be
sufficient. Test 512, 1024, 2048, 4096, and 8192. You should see your
throughput go up and then back down. Find the sweet spot and use that
value. If two of these yield throughput within 5% of one another, use
the lower value as it eats less RAM.
--
Stan
next prev parent reply other threads:[~2013-12-06 9:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-05 19:24 RAID-0/5/6 performances Piergiorgio Sartor
2013-12-05 21:57 ` NeilBrown
2013-12-05 22:29 ` Piergiorgio Sartor
2013-12-06 22:47 ` Piergiorgio Sartor
2013-12-06 9:24 ` Stan Hoeppner [this message]
2013-12-06 18:13 ` Piergiorgio Sartor
2013-12-06 23:29 ` Stan Hoeppner
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