From: Bernd Schubert <bernd.schubert@fastmail.fm>
To: stan@hardwarefreak.com,
Jeff Allison <jeff.allison@allygray.2y.net>,
linux-raid@vger.kernel.org
Subject: Re: raid resync speed
Date: Thu, 20 Mar 2014 16:35:24 +0100 [thread overview]
Message-ID: <532B0ABC.5040604@fastmail.fm> (raw)
In-Reply-To: <532AFCC8.6080902@hardwarefreak.com>
>
> Yes. The article gives 16384 and 32768 as examples for
> stripe_cache_size. Such high values tend to reduce throughput instead
> of increasing it. Never use a value above 2048 with rust, and 1024 is
> usually optimal for 7.2K drives. Only go 4096 or higher with SSDs. In
> addition, high values eat huge amounts of memory. The formula is:
>
Why should the stripe-cache size differ between SSDs and rotating disks?
Did you ever try to figure out yourself why it got slower with higher
values? I profiled that in the past and it was a CPU/memory limitation -
the md thread went to 100%, searching for stripe-heads.
So I really wonder how you got the impression that the stripe cache size
should have different values for differnt kinds of drives.
Cheers,
Bernd
next prev parent reply other threads:[~2014-03-20 15:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-20 1:12 raid resync speed Jeff Allison
2014-03-20 14:35 ` Stan Hoeppner
2014-03-20 15:35 ` Bernd Schubert [this message]
2014-03-20 15:36 ` Bernd Schubert
2014-03-20 16:19 ` Eivind Sarto
2014-03-20 16:22 ` Bernd Schubert
2014-03-20 18:44 ` Stan Hoeppner
2014-03-27 16:08 ` Bernd Schubert
2014-03-28 8:03 ` Stan Hoeppner
2014-03-20 17:46 ` Bernd Schubert
2014-03-21 0:44 ` Jeff Allison
-- strict thread matches above, loose matches on Subject: below --
2005-09-10 2:11 RAID " Eyal Lebedinsky
2005-09-10 2:53 ` Nuno Silva
2005-09-10 3:18 ` Eyal Lebedinsky
2005-09-10 4:54 ` Nuno Silva
2005-09-10 5:16 ` Joel Jaeggli
2005-09-11 2:16 ` Eyal Lebedinsky
2005-09-12 15:57 ` Roger Heflin
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