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From: Hugo Mills <hugo@carfax.org.uk>
To: Lester B <b.lester011+btrfs@gmail.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Total fs size does not match with the actual size of the setup
Date: Sun, 27 Oct 2013 20:17:50 +0000	[thread overview]
Message-ID: <20131027201750.GG31029@carfax.org.uk> (raw)
In-Reply-To: <CAOeUAF_msDRoi2CDnAhwqC+=_oqNqH0=94+N9qjXpi4m4ChVLg@mail.gmail.com>

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On Mon, Oct 28, 2013 at 04:09:18AM +0800, Lester B wrote:
> The btrfs setup only have one device of size 7 GiB but
> when I run df, the total size shown is 15 GiB. Running
> btrfs --repair

   I'd recommend not running btrfs check --repair unless you really
know what you're doing, or you've checked with someone knowledgable
and they say you should try it. On a non-broken filesystem (as here),
it's probably OK, though.

> displays an error "cache and super
> generation don't match, space cache will be invalidated."

   This is harmless.

> How can I correct the total fs size as shown in df?

   You can't. It's an artefact of the fact that you've got a RAID-1
(or RAID-10, or --mixed and DUP) filesystem, and that the standard
kernel interface for df doesn't allow us to report the correct figures
-- see [1] (and the subsequent entry as well) for a more detailed
description.

   Hugo.

[1] https://btrfs.wiki.kernel.org/index.php/FAQ#Why_does_df_show_incorrect_free_space_for_my_RAID_volume.3F

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
  PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
         --- Nothing right in my left brain. Nothing left in ---         
                             my right brain.                             

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  reply	other threads:[~2013-10-27 20:17 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-27 20:09 Total fs size does not match with the actual size of the setup Lester B
2013-10-27 20:17 ` Hugo Mills [this message]
2013-10-27 20:27   ` Lester B
2013-10-27 21:34     ` Brendan Hide
2013-10-27 21:49       ` Lester B

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