From: Paul Clements <paul.clements@steeleye.com>
To: linux-raid@vger.kernel.org
Subject: Re: question about bitmaps and dirty percentile
Date: Mon, 03 Aug 2009 16:30:14 -0400 [thread overview]
Message-ID: <4A7748D6.7060307@steeleye.com> (raw)
In-Reply-To: <h57469$u6a$2@ger.gmane.org>
Matthias Urlichs wrote:
> On Fri, 31 Jul 2009 14:09:06 -0500, Jon Nelson wrote:
>
>>> The bitmap never gets cleared unless all disks in the array are in
>>> sync.
>> Well, that sucks. What is the reasoning behind that?
>
> There's only one bitmap per device. If the bits get cleaned writing to
> disk #2, then the system would forget that they still need to be written
> to disk #3.
Right, and that decision was made for efficiency and simplicity of
design. Having a bitmap per pair of component disks would be inefficient
and very complicated. You could stack raid1's if you absolutely had to
have that type of functionality.
--
Paul
next prev parent reply other threads:[~2009-08-03 20:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-30 18:25 question about bitmaps and dirty percentile Jon Nelson
2009-07-30 19:16 ` Jon Nelson
2009-07-31 18:17 ` Paul Clements
2009-07-31 19:09 ` Jon Nelson
2009-08-03 16:44 ` Matthias Urlichs
2009-08-03 20:30 ` Paul Clements [this message]
2009-08-06 6:21 ` Neil Brown
2009-08-06 13:02 ` Jon Nelson
2009-08-07 1:47 ` NeilBrown
2009-08-07 2:17 ` Jon Nelson
2009-08-07 12:29 ` John Robinson
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