From: Milan Broz <gmazyland@gmail.com>
To: NeilBrown <neilb@suse.de>
Cc: Phil Turmel <philip@turmel.org>,
Christoph Anton Mitterer <calestyo@scientia.net>,
linux-raid@vger.kernel.org
Subject: Re: some general questions on RAID
Date: Mon, 08 Jul 2013 07:25:53 +0200 [thread overview]
Message-ID: <51DA4D61.2090708@gmail.com> (raw)
In-Reply-To: <20130708145316.4486d0dc@notabene.brown>
On 07/08/2013 06:53 AM, NeilBrown wrote:
> On Sun, 07 Jul 2013 19:39:27 +0200 Milan Broz <gmazyland@gmail.com> wrote:
>
>
>> So if you have multiple IOs submitted in parallel from *different* CPUs,
>> they are processed in parallel.
>>
>> If you have MD over dmcrypt, this can cause problem that MD sumbits all IOs
>> with the same cpu context and dmcrypt cannot run it in parallel.
>
> For RAID1 and RAID10 this isn't true any more.
>
> Commit f54a9d0e59c4bea3db733921ca9147612a6f292c
> in 3.6 changed this for RAID1 and a similar commit did for RAID10.
> RAID4/5/6 still submit from a single thread as you say.
Ah, sorry, missed that change, thanks Neil!
So then it should perform much better.
(But IIRC most reports about dmcrypt performance was either over
high-speed SSD without AES-NI or over RAID5 - case like huge ftp archive
where they need redundancy & offline data security.
But here current design should be help...)
Milan
next prev parent reply other threads:[~2013-07-08 5:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-04 18:30 some general questions on RAID Christoph Anton Mitterer
2013-07-04 22:07 ` Phil Turmel
2013-07-04 23:34 ` Christoph Anton Mitterer
2013-07-08 4:48 ` NeilBrown
2013-07-06 1:33 ` Christoph Anton Mitterer
2013-07-06 8:52 ` Stan Hoeppner
2013-07-06 15:15 ` Christoph Anton Mitterer
2013-07-07 16:51 ` Stan Hoeppner
2013-07-07 17:39 ` Milan Broz
2013-07-07 18:01 ` Christoph Anton Mitterer
2013-07-07 18:50 ` Milan Broz
2013-07-07 20:51 ` Christoph Anton Mitterer
2013-07-08 5:40 ` Milan Broz
2013-07-08 4:53 ` NeilBrown
2013-07-08 5:25 ` Milan Broz [this message]
2013-07-05 1:13 ` Brad Campbell
2013-07-05 1:39 ` Sam Bingner
2013-07-05 3:06 ` Brad Campbell
2013-07-06 1:23 ` some general questions on RAID (OT) Christoph Anton Mitterer
2013-07-06 6:23 ` Sam Bingner
2013-07-06 15:11 ` Christoph Anton Mitterer
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