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From: Andy Smith <andy@strugglers.net>
To: list Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: raid10 redundancy
Date: Thu, 13 May 2021 15:38:22 +0000	[thread overview]
Message-ID: <20210513153822.n74ezf5jav3ywuqn@bitfolk.com> (raw)
In-Reply-To: <20210512172242.GX1415@justpickone.org>

Hello,

On Wed, May 12, 2021 at 01:22:42PM -0400, David T-G wrote:
> RAID10 is striping AND mirroring (leaving out for the moment the distinction
> of striping mirrors vs mirroring stripes).  How can one have both with only
> two disks??  You either stripe the two disks together for more storage or
> mirror them for redundant storage, but I just don't see how one could do both.

Linux RAID-1 is a mirror - all devices are identical. A reading
thread picks a device and reads from it. You get up to 1 device
worth of IOPS.

Linux RAID-10 splits the data into chunks and stripes them across
the devices with as many copies as desired (default 2). So a single
threaded reader can get up to n devices worth of IOPS.

When n is 2 and there's only 2 identical devices and the load is
multi-thread/process then you may not see much difference. Measure
it and let us know!

Cheers,
Andy

  parent reply	other threads:[~2021-05-13 15:38 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-06  5:09 raid10 redundancy d tbsky
2021-05-06  7:48 ` Xiao Ni
2021-05-06  9:57   ` d tbsky
2021-05-06 12:38     ` Reindl Harald
2021-05-07  1:28       ` d tbsky
2021-05-08 13:47         ` keld
2021-05-09  0:52           ` Phillip Susi
2021-05-12 17:22             ` David T-G
2021-05-12 17:26               ` Reindl Harald
2021-05-12 17:39                 ` David T-G
2021-05-13 15:38               ` Andy Smith [this message]
2021-05-13 15:46               ` Phillip Susi
2021-05-13 15:59                 ` Andy Smith
2021-05-14 14:28                   ` Phillip Susi
2021-05-14 14:37                     ` Andy Smith
2021-05-17  2:07                       ` Brad Campbell
2021-05-06 13:09     ` Phillip Susi
2021-05-07  1:47       ` d tbsky
     [not found]         ` <86A76859-3098-4AB8-9AE7-46FF54736B88@websitemanagers.com.au>
2021-05-07  3:05           ` d tbsky
2021-05-07  3:26         ` Reindl Harald
2021-05-07 14:53         ` Andy Smith
2021-05-08  1:54           ` d tbsky
2021-05-08  5:55             ` Andy Smith
2021-05-09  1:10         ` Phillip Susi
2021-05-07  1:26     ` d tbsky
2021-05-06 10:39 ` Peter Grandi
2021-05-07  1:37   ` d tbsky
     [not found] ` <AD8C004B-FE83-4ABD-B58A-1F7F8683CD1F@websitemanagers.com.au>
2021-05-07  1:12   ` d tbsky
2021-05-07  9:46     ` Wols Lists
2021-05-11  0:04       ` Phil Turmel
2021-05-12 17:27         ` David T-G
2021-05-12 18:20           ` Phil Turmel
2021-05-12 16:31 ` Roy Sigurd Karlsbakk
2021-05-13 15:38   ` Phillip Susi
2021-05-13 18:21     ` Phil Turmel
2021-05-14 14:30       ` Phillip Susi
2021-05-14 14:48         ` Roy Sigurd Karlsbakk
2021-05-17 20:50           ` Phillip Susi
2021-05-17 22:21             ` Wols Lists
2021-05-18  0:12               ` Phil Turmel
2021-05-18 16:05               ` Phillip Susi
2021-05-18 17:38                 ` Reindl Harald
2021-05-18 18:51                   ` Phillip Susi
2021-05-18 19:02                     ` Reindl Harald
2021-05-18 23:48                 ` antlists
2021-05-19  3:42                   ` Adam Goryachev
2021-05-19 13:02                     ` Phillip Susi
2021-05-19 21:19                       ` Reindl Harald
2021-05-20  1:32                       ` Adam Goryachev
     [not found]                         ` <CAAMCDeeOnraMDNCF6ZZqPAxUrih2gSse1wDYgOfd1LqY-Ffqxw@mail.gmail.com>
2021-05-20 15:08                           ` antlists

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