From: "Keld Jørn Simonsen" <keld@dkuug.dk>
To: Bill Davidsen <davidsen@tmr.com>
Cc: Christian Pernegger <pernegger@gmail.com>,
Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: raid10 vs raid5 - strange performance
Date: Sun, 30 Mar 2008 10:55:28 +0200 [thread overview]
Message-ID: <20080330085528.GC17756@rap.rap.dk> (raw)
In-Reply-To: <47EEA5BB.5080106@tmr.com>
On Sat, Mar 29, 2008 at 04:25:31PM -0400, Bill Davidsen wrote:
> Christian Pernegger wrote:
>
> The md raid10,f2 generally has modest write performance, if U is a
> single drive speed, write might range between 1.5U to (N-1)/2*U
> depending on tuning. Read speed is almost always (N-1)*U, which is great
> for many applications. Playing with chunk size, chunk buffers, etc, can
> make a large difference in write performance.
Hmm, I have other formulae for this. raid10,f2 write speed would rather
be U*N/2, and read speed be U*N - possibly enhanced by also having
bigger chunks than on a regular non-raid disk, and enhanced by lower
access times. The formulae are bothe for sequential and random reads.
Best regards
keld
next prev parent reply other threads:[~2008-03-30 8:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-25 21:33 raid10 vs raid5 - strange performance Christian Pernegger
2008-03-25 22:13 ` David Rees
2008-03-25 22:56 ` Christian Pernegger
2008-03-26 16:29 ` Bill Davidsen
2008-03-26 17:10 ` Christian Pernegger
2008-03-26 17:49 ` Keld Jørn Simonsen
2008-03-25 23:36 ` Keld Jørn Simonsen
[not found] ` <bb145bd20803251837x7ef1fa9dk6191fcaea7b02144@mail.gmail.com>
[not found] ` <20080326072416.GA8674@rap.rap.dk>
2008-03-26 17:16 ` Christian Pernegger
2008-03-26 19:29 ` Keld Jørn Simonsen
2008-03-27 1:11 ` Christian Pernegger
2008-03-27 9:18 ` Keld Jørn Simonsen
[not found] ` <47EAACAB.7070203@tmr.com>
2008-03-27 2:02 ` Christian Pernegger
2008-03-29 20:25 ` Bill Davidsen
2008-03-29 21:26 ` Iustin Pop
2008-03-30 8:55 ` Keld Jørn Simonsen [this message]
2008-03-30 9:34 ` Keld Jørn Simonsen
2008-03-30 11:16 ` Peter Grandi
2008-03-30 12:58 ` Keld Jørn Simonsen
2008-03-30 14:21 ` Keld Jørn Simonsen
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