Btrfs shows incorrect disk size after running a replace command

Btrfs shows incorrect disk size after running a replace command

[Kyle Bentley]

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I have just recently replaced two 750 GB disks with two 1 TB disks.  I
used the replace command to do so, aka "btrfs replace start /dev/sdX
/dev/sdY /mountpoint".  Each replacement went smoothly, with no errors
reporting.  I'm positive that the source and destination drives were
identified correctly.  However, when I run "btrfs filesystem show", the
output is

Label: none  uuid: b2dbc0e4-94fc-4089-9221-d79d7919f8cb
    Total devices 2 FS bytes used 494.23GB
    devid    2 size 698.64GB used 495.03GB path /dev/sda
    devid    1 size 698.64GB used 495.03GB path /dev/sdb

Btrfs v0.20-rc1

The disks show up as the 750 GB, when they are in fact 1 TB.  smartctl
for each drive shows

root@Lore:/home/kyle# smartctl -i /dev/sda |grep "User Capacity"
User Capacity:    1,000,204,886,016 bytes [1.00 TB]

root@Lore:/home/kyle# smartctl -i /dev/sdb |grep "User Capacity"
User Capacity:    1,000,204,886,016 bytes [1.00 TB]

Is there any harm in this?  If it is simply a superficial bug I will not
worry.  Would running a balance help?  As for the specifics, I'm using

Debian testing x64
Vanilla kernel 3.13.0
AMD hardware

Thanks,

Kyle Bentley

- ---------------------------------------
kwbent@uab.edu
UAB Dept of Physics
1300 University Blvd
CH 310
Birmingham, AL
- ---------------------------------------



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Re: Btrfs shows incorrect disk size after running a replace command

[Andreas Fischer]

Hello Kyle,

you will probably have to tell btrfs to use the complete devices.
Checkout "btrfs filesystem resize". There are cases when one does not
want to grow the used space on a replacement disk automatically, e.g.
when the disk is to be replaced with a smaller disk again, so this is
not a bug.

Cheers,
Andreas

On Tue, Jan 21, 2014 at 2:35 PM, Kyle Bentley <kwbent@uab.edu> wrote:
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> I have just recently replaced two 750 GB disks with two 1 TB disks.  I
> used the replace command to do so, aka "btrfs replace start /dev/sdX
> /dev/sdY /mountpoint".  Each replacement went smoothly, with no errors
> reporting.  I'm positive that the source and destination drives were
> identified correctly.  However, when I run "btrfs filesystem show", the
> output is
>
> Label: none  uuid: b2dbc0e4-94fc-4089-9221-d79d7919f8cb
>     Total devices 2 FS bytes used 494.23GB
>     devid    2 size 698.64GB used 495.03GB path /dev/sda
>     devid    1 size 698.64GB used 495.03GB path /dev/sdb
>
> Btrfs v0.20-rc1
>
> The disks show up as the 750 GB, when they are in fact 1 TB.  smartctl
> for each drive shows
>
> root@Lore:/home/kyle# smartctl -i /dev/sda |grep "User Capacity"
> User Capacity:    1,000,204,886,016 bytes [1.00 TB]
>
> root@Lore:/home/kyle# smartctl -i /dev/sdb |grep "User Capacity"
> User Capacity:    1,000,204,886,016 bytes [1.00 TB]
>
> Is there any harm in this?  If it is simply a superficial bug I will not
> worry.  Would running a balance help?  As for the specifics, I'm using
>
> Debian testing x64
> Vanilla kernel 3.13.0
> AMD hardware
>
> Thanks,
>
> Kyle Bentley
>
> - ---------------------------------------
> kwbent@uab.edu
> UAB Dept of Physics
> 1300 University Blvd
> CH 310
> Birmingham, AL
> - ---------------------------------------
>
>
>
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