From: NeilBrown <neilb@suse.de>
To: "Mathias Burén" <mathias.buren@gmail.com>
Cc: Linux-RAID <linux-raid@vger.kernel.org>
Subject: Re: External bitmap, questions
Date: Sat, 19 Feb 2011 15:49:24 +1100 [thread overview]
Message-ID: <20110219154924.2218c87c@notabene.brown> (raw)
In-Reply-To: <AANLkTinb3TvJr_-GPjMhXsyA-zwkf45GRAfpb7+Xio6H@mail.gmail.com>
On Sat, 19 Feb 2011 00:47:10 +0000 Mathias Burén <mathias.buren@gmail.com>
wrote:
> Hi,
>
> >From the mdadm manual:
>
> "-b, --bitmap=
> [...]
> Note: external bitmaps are only known to work on ext2 and ext3.
> Storing bitmap files on other filesystems may result in serious
> problems."
>
> I was planning to store the external bitmap on an ext4 partition. Will
> this be a problem, or is the warning there because it hasn't been
> tested enough but no problems found?
External bitmaps use 'BMAP' to find where the file lives on the device and
then writes directly to the device - not through the filesystem.
So as long as there is no tail-packing to block migration happening it should
work fine.
I haven't looked inside ext4 but I am fairly confident that external bitmaps
will work properly.
NeilBrown
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next prev parent reply other threads:[~2011-02-19 4:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-19 0:47 External bitmap, questions Mathias Burén
2011-02-19 4:49 ` NeilBrown [this message]
2011-02-19 4:55 ` Mathias Burén
2011-02-19 5:30 ` NeilBrown
2011-02-19 5:42 ` Mathias Burén
2011-02-19 12:14 ` Roman Mamedov
2011-02-19 12:20 ` Mathias Burén
2011-02-19 12:32 ` Roman Mamedov
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