From: Stan Hoeppner <stan@hardwarefreak.com>
To: keld@keldix.com
Cc: Phil Turmel <philip@turmel.org>, Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: "Missing" RAID devices
Date: Fri, 24 May 2013 02:37:01 -0500 [thread overview]
Message-ID: <519F189D.6030103@hardwarefreak.com> (raw)
In-Reply-To: <20130524063228.GB30833@www5.open-std.org>
On 5/24/2013 1:32 AM, keld@keldix.com wrote:
> On Thu, May 23, 2013 at 10:45:56PM -0500, Stan Hoeppner wrote:
>> On 5/23/2013 3:30 AM, keld@keldix.com wrote:
>>> On Thu, May 23, 2013 at 12:59:39AM -0500, Stan Hoeppner wrote:
>>
>>>> You may be tempted to use md/RAID10 of some layout
>>>> to optimize for writes, but you'd gain nothing, and you'd lose some
>>>> performance due to overhead. The partitions you'll be using in this
>>>> case are so small that they easily fit in a single physical disk track,
>>>> thus no head movement is required to seek between sectors, only rotation
>>>> of the platter.
>> ...
>>> I think a raid10,far3 is a good choice for swap, then you will enjoy
>>> RAID0-like reading speed. and good write speed (compared to raid6),
>>> and a chance of live surviving if just one drive keeps functioning.
>>
>> As I mention above, none of the md/RAID10 layouts will yield any added
>> performance benefit for swap partitions. And I state the reason why.
>> If you think about this for a moment you should reach the same conclusion.
>
> I think it is you who are not fully aquainted with Linux MD. Linux
> MD RAID10,far3 offers improved performance in single read,
On most of today's systems, read performance is largely irrelevant WRT
swap performance. However write performance is critical. None of the
md/RAID10 layouts are going to increase write throughput over RAID1
pairs. And all the mirrored RAIDs will be 2x slower than interleaved
swap across direct disk partitions.
--
Stan
next prev parent reply other threads:[~2013-05-24 7:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-21 12:51 "Missing" RAID devices Jim Santos
2013-05-21 15:31 ` Phil Turmel
2013-05-21 22:22 ` Jim Santos
2013-05-22 0:02 ` Phil Turmel
2013-05-22 0:16 ` Jim Santos
2013-05-22 22:43 ` Stan Hoeppner
2013-05-22 23:26 ` Phil Turmel
2013-05-23 5:59 ` Stan Hoeppner
2013-05-23 8:30 ` keld
2013-05-24 3:45 ` Stan Hoeppner
2013-05-24 6:32 ` keld
2013-05-24 7:37 ` Stan Hoeppner [this message]
2013-05-24 17:15 ` keld
2013-05-24 19:05 ` Stan Hoeppner
2013-05-24 19:22 ` keld
2013-05-25 1:42 ` Stan Hoeppner
2013-05-24 9:23 ` David Brown
2013-05-24 18:03 ` keld
2013-05-23 8:22 ` David Brown
2013-05-21 16:23 ` Doug Ledford
2013-05-21 17:03 ` Drew
[not found] ` <519BDC8C.1040202@hardwarefreak.com>
2013-05-21 21:02 ` Drew
2013-05-21 22:06 ` Stan Hoeppner
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