From: John Robinson <john.robinson@anonymous.org.uk>
To: Liam Kurmos <quantum.leaf@gmail.com>
Cc: Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: mdadm raid1 read performance
Date: Wed, 04 May 2011 01:57:28 +0100 [thread overview]
Message-ID: <4DC0A478.9010704@anonymous.org.uk> (raw)
In-Reply-To: <BANLkTim8Ehn0fANtibg7X1cMVvOgt7CNMA@mail.gmail.com>
On 04/05/2011 01:07, Liam Kurmos wrote:
> Hi,
>
> I've been testing mdadm (great piece of software btw) however all my
> test show that reading from raid1 is only the same speed as reading
> from a single drive.
>
> Is this a known issue? or is there something seriously wrong with my
> system? i have tried v2.8.1 and v.3.2.1 without difference and several
> benchmarking methods.
This is a FAQ. Yes, this is known. No, it's not an issue, it's by design
- pretty much any RAID 1 implementation will be the same because of the
nature of spinning discs. md RAID 1 will serve multiple simultaneous
reads from the different mirrors, giving a higher total throughput, but
a single-threaded read will read from only one. If you want RAID 0
sequential speed at the same time as RAID 1 mirroring, look at md RAID
10, and in particular RAID 10,f2; please see the excellent documentation
and wiki for more details.
Cheers,
John.
next prev parent reply other threads:[~2011-05-04 0:57 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-04 0:07 mdadm raid1 read performance Liam Kurmos
2011-05-04 0:57 ` John Robinson [this message]
2011-05-06 20:44 ` Leslie Rhorer
2011-05-06 21:56 ` Keld Jørn Simonsen
2011-05-04 0:58 ` NeilBrown
2011-05-04 5:30 ` Drew
2011-05-04 6:31 ` Brad Campbell
2011-05-04 7:42 ` Roberto Spadim
2011-05-04 23:08 ` Liam Kurmos
2011-05-04 23:35 ` Roberto Spadim
2011-05-04 23:36 ` Brad Campbell
2011-05-04 23:45 ` NeilBrown
2011-05-04 23:57 ` Roberto Spadim
2011-05-05 0:14 ` Liam Kurmos
2011-05-05 0:20 ` Liam Kurmos
2011-05-05 0:25 ` Roberto Spadim
2011-05-05 0:40 ` Liam Kurmos
2011-05-05 7:26 ` David Brown
2011-05-05 10:41 ` Keld Jørn Simonsen
2011-05-05 11:38 ` David Brown
2011-05-06 4:14 ` CoolCold
2011-05-06 7:29 ` David Brown
2011-05-06 21:05 ` Leslie Rhorer
2011-05-07 10:37 ` David Brown
2011-05-07 10:58 ` Keld Jørn Simonsen
2011-05-05 0:24 ` Roberto Spadim
2011-05-05 11:10 ` Keld Jørn Simonsen
2011-05-06 21:20 ` Leslie Rhorer
2011-05-06 21:53 ` Keld Jørn Simonsen
2011-05-07 3:17 ` Leslie Rhorer
2011-05-05 4:06 ` Roman Mamedov
2011-05-05 8:06 ` Nikolay Kichukov
2011-05-05 8:39 ` Liam Kurmos
2011-05-05 8:49 ` Liam Kurmos
2011-05-05 9:30 ` NeilBrown
2011-05-04 7:48 ` David Brown
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