linux-ext4 - Re: fallocate creating fragmented files

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Message-Id: <1359586176.29975.140661184693725.5AA32A9C@webmail.messagingengine.com>
Date:	Thu, 31 Jan 2013 09:49:36 +1100
From:	Robert Mueller <robm@...tmail.fm>
To:	Bron Gondwana <brong@...tmail.fm>, "Theodore Ts'o" <tytso@....edu>
Cc:	Eric Sandeen <sandeen@...hat.com>,
	Linux Ext4 mailing list <linux-ext4@...r.kernel.org>
Subject: Re: fallocate creating fragmented files


> It's the twoskip files that we're particularly concerned about.  Not
> so much that they fragment during use, that's kind of expected - but
> that a repack doesn't result in a single contiguous file.  Apart from
> the header, I can't see why it doesn't.

Well yes, this is ultimately what we're worried about, but we did some
digging and found that even just fallocating a file creates a very
fragmented file.

I think it's better to try and work out why just fallocating space for
files is creating such fragmented files, it's certainly a simpler test
case to try and get information on first.

Rob
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