From: Stephane Chazelas <stephane.chazelas@gmail.com>
To: Miao Xie <miaox@cn.fujitsu.com>
Cc: Hugo Mills <hugo-lkml@carfax.org.uk>,
helmut@hullen.de, linux-btrfs@vger.kernel.org
Subject: Re: wrong values in "df" and "btrfs filesystem df"
Date: Mon, 11 Apr 2011 08:29:46 +0100 [thread overview]
Message-ID: <chaz20110411072946.GA5587@seebyte.com> (raw)
In-Reply-To: <4DA182DF.6010703@cn.fujitsu.com>
2011-04-10 18:13:51 +0800, Miao Xie:
[...]
> >> # df /srv/MM
> >>
> >> Filesystem 1K-blocks Used Available Use% Mounted on
> >> /dev/sdd1 5846053400 1593436456 2898463184 36% /srv/MM
> >>
> >> # btrfs filesystem df /srv/MM
> >>
> >> Data, RAID0: total=1.67TB, used=1.48TB
> >> System, RAID1: total=16.00MB, used=112.00KB
> >> System: total=4.00MB, used=0.00
> >> Metadata, RAID1: total=3.75GB, used=2.26GB
> >>
> >> # btrfs-show
> >>
> >> Label: MMedia uuid: 120b036a-883f-46aa-bd9a-cb6a1897c8d2
> >> Total devices 3 FS bytes used 1.48TB
> >> devid 3 size 1.81TB used 573.76GB path /dev/sdb1
> >> devid 2 size 1.81TB used 573.77GB path /dev/sde1
> >> devid 1 size 1.82TB used 570.01GB path /dev/sdd1
> >>
> >> Btrfs Btrfs v0.19
> >>
> >> ------------------------------------------------
> >>
> >> "df" shows an "Available" value which isn't related to any real value.
> >
> > I _think_ that value is the amount of space not allocated to any
> > block group. If that's so, then Available (from df) plus the three
> > "total" values (from btrfs fi df) should equal the size value from df.
>
> This value excludes the space that can not be allocated to any block group,
> This feature was implemented to fix the bug df command add the disk space, which
> can not be allocated to any block group forever, into the "Available" value.
> (see the changelog of the commit 6d07bcec969af335d4e35b3921131b7929bd634e)
>
> This implementation just like fake chunk allocation, but the fake allocation
> just allocate the space from two of these three disks, doesn't spread the
> stripes over all the disks, which has enough space.
[...]
Hi Miao,
would you care to expand a bit on that. In Helmut's case above
where all the drives have at least 1.2TB free, how would there
be un-allocatable space?
What's the implication of having disks of differing sizes? Does
that mean that the extra space on larger disks is lost?
Thanks,
Stephane
next prev parent reply other threads:[~2011-04-11 7:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-09 6:25 wrong values in "df" and "btrfs filesystem df" Helmut Hullen
2011-04-09 9:11 ` Hugo Mills
2011-04-09 9:46 ` Stephane Chazelas
2011-04-09 12:28 ` Helmut Hullen
2011-04-09 16:36 ` Calvin Walton
2011-04-09 17:05 ` Helmut Hullen
2011-04-09 17:26 ` Calvin Walton
2011-04-09 18:15 ` Helmut Hullen
2011-04-09 19:35 ` Peter Stuge
2011-04-09 20:38 ` Hugo Mills
2011-04-10 10:13 ` Miao Xie
2011-04-11 7:29 ` Stephane Chazelas [this message]
2011-04-11 7:56 ` Arne Jansen
2011-04-11 9:06 ` Helmut Hullen
2011-04-12 7:22 ` Miao Xie
2011-04-12 8:17 ` Stephane Chazelas
2011-04-13 5:35 ` Miao Xie
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