From: Neil Brown <neilb@suse.de>
To: Nagilum <nagilum@nagilum.org>
Cc: linux-raid <linux-raid@vger.kernel.org>
Subject: Re: Problem re-shaping RAID6
Date: Thu, 17 Jun 2010 15:47:08 +1000 [thread overview]
Message-ID: <20100617154708.227cd303@notabene.brown> (raw)
In-Reply-To: <20100614124723.84152dz5al8096f4@cakebox.homeunix.net>
On Mon, 14 Jun 2010 12:47:23 +0200
Nagilum <nagilum@nagilum.org> wrote:
>
> ----- Message from neilb@suse.de ---------
> Date: Mon, 14 Jun 2010 09:15:18 +1000
> From: Neil Brown <neilb@suse.de>
> Subject: Re: Problem re-shaping RAID6
> To: Jérôme Poulin <jeromepoulin@gmail.com>
> Cc: linux-raid <linux-raid@vger.kernel.org>
>
>
> > Thanks.
> > I fixed this bug a slightly different way
> >
> > - blocks = ochunk/512 * nchunk/512 * odata * ndata / a;
> > + blocks = (ochunk/512) * (nchunk/512) * odata * ndata / a;
> >
> >
> > See
> > http://neil.brown.name/git?p=mdadm;a=commitdiff;h=200871adf9e15d5ad985f28c349fd89c386ef48a
>
> Those static numbers always make my nose wrinkle.
> Don't we have the blocksize somewhere already? I'm also concerned what
> happens when true 4k sectors are used..
>
A sector will always be 512 bytes to Linux, even when we have drives that can
only do IO in multiples of 8 sectors. Changing that would cause way to many
headaches.
Yes, I could possibly use a define for '512'. Some times that is
appropriate, but I thing 512 is so clearly "bytes_per_sector" it would just
add an unnecessary level of indirection.
It is a question of taste really - no right answers.
Thanks,
NeilBrown
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next prev parent reply other threads:[~2010-06-17 5:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-13 19:15 Problem re-shaping RAID6 Jérôme Poulin
2010-06-13 23:15 ` Neil Brown
2010-06-14 10:47 ` Nagilum
2010-06-17 5:47 ` Neil Brown [this message]
2010-06-17 8:20 ` Michael Evans
2010-06-18 10:53 ` Nagilum
[not found] ` <4C1BBE6E.5090802@tmr.com>
2010-06-29 1:11 ` Neil Brown
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