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To: gentoo-dev@g.o
From: Nirbheek Chauhan <nirbheek@g.o>
Subject: Re: Re: proj/portage:master commit in: pym/portage/dbapi/
Date: Sat, 26 Nov 2011 21:20:57 +0530
On Sat, Nov 26, 2011 at 7:14 PM, Rich Freeman <rich0@g.o> wrote:
> isn't supported.  It is available in stable coreutils.  Some speculate
> that this option could increase fragmentation (both copies will share
> extents from the original file, and have some extents of their own),
> but btrfs doesn't overwrite anything in-place so fragmentation is a
> potential issue with any file modification (change one byte in the

Adding to your comments on this:

To mitigate such issues, newer versions of the btrfs fs driver have
automatic online defragmentation as well. Works quite well for
moderate fragmentation.

A particularly ghastly example where fragmentation issues become
pathological in nature are files that are fsync()ed very frequently. A
typical example are the *.sqlite files in ~/.mozilla which easily get
hundreds or even thousands of fragments after a few hours worth of
firefox usage (can be verified with filefrag).

To fix such things, regular online defragmentation of those specific
files can be done using `btrfs fi defrag <file>`.

-- 
~Nirbheek Chauhan

Gentoo GNOME+Mozilla Team


References:
Re: proj/portage:master commit in: pym/portage/dbapi/
-- Fabian Groffen
Re: Re: proj/portage:master commit in: pym/portage/dbapi/
-- Nirbheek Chauhan
Re: proj/portage:master commit in: pym/portage/dbapi/
-- Nirbheek Chauhan
Re: Re: proj/portage:master commit in: pym/portage/dbapi/
-- Ciaran McCreesh
Re: Re: proj/portage:master commit in: pym/portage/dbapi/
-- Rich Freeman
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Updated Jun 29, 2012

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