Strangeness on btrfs balance..

Strangeness on btrfs balance..

[Evert Vorster]

Hi there...

I have kernel version 2.6.36.3, compiled with gcc 4.4.5, btrfstools
version 0.19+20101101

I have a btrfs filesystem (/data) consisting of two 1TB hard disks, raid0.

I added in another 1TB hard drive.

root@X86-64:~# btrfs filesystem show
failed to read /dev/sdh
failed to read /dev/sdg
failed to read /dev/sdf
failed to read /dev/sde
failed to read /dev/sr0
failed to read /dev/fd0u800
failed to read /dev/fd0
Label: none  uuid: 91a3ca88-7883-45a1-b83d-d95bf98a1d51
        Total devices 3 FS bytes used 1.20TB
        devid    3 size 931.51GB used 0.00 path /dev/sdb
        devid    1 size 931.51GB used 889.15GB path /dev/sdc
        devid    2 size 931.51GB used 889.13GB path /dev/sdd

Btrfs Btrfs v0.19

Sat Feb 05 03:22:29
root@X86-64:~#
----------------------------------------------------
So, I want to balance my data across these three devices, but I
noticed an inconsistencybteween "man btrfs" and btrfs' help...

root@X86-64:~# man btrfs | grep balance
       btrfs device balance <path>
       device balance <path>

Sat Feb 05 03:23:50

and

Sat Feb 05 03:24:19
root@X86-64:~# btrfs | grep balance
        btrfs filesystem balance <path>

Sat Feb 05 03:24:20

According to the man page, to balance a filesystem, the command is:
btrfs device balance <path>
In my case: btrfs device balance /data
This returns an error:

root@X86-64:~# btrfs device balance /data
ERROR: unknown command 'device'

When I try with
btrfs filesystem balance /data, I can see data being read and written
to the two original disks, but the new disk is not getting written to.
I keep an eye on disk IO with gkrellm. Also, after about an hour of
balancing, /dev/sdb is still completely empty.

Any idea of why this is happening?
Last few lines of dmesg:
floppy0: disk absent or changed during operation
end_request: I/O error, dev fd0, sector 128
end_request: I/O error, dev fd0, sector 0
btrfs: found 69 extents
btrfs: relocating block group 1897465380864 flags 9
btrfs: found 95 extents
btrfs: found 95 extents
btrfs: relocating block group 1895317897216 flags 9
btrfs: found 81 extents
btrfs: found 81 extents
btrfs: relocating block group 1893170413568 flags 9
btrfs: found 93 extents
btrfs: found 93 extents
btrfs: relocating block group 1891022929920 flags 9
btrfs: found 96 extents
btrfs: found 96 extents
btrfs: relocating block group 1888875446272 flags 9
btrfs: found 93 extents
btrfs: found 93 extents
btrfs: relocating block group 1886727962624 flags 9
btrfs: found 90 extents
btrfs: found 90 extents
btrfs: relocating block group 1884580478976 flags 9
btrfs: found 99 extents
btrfs: found 99 extents
btrfs: relocating block group 1882432995328 flags 9
btrfs: found 1 extents
btrfs: found 1 extents
btrfs: relocating block group 1880285511680 flags 9
btrfs: found 101 extents
btrfs: found 101 extents
btrfs: relocating block group 1878138028032 flags 9
btrfs: found 105 extents
btrfs: found 105 extents
btrfs: relocating block group 1875990544384 flags 9
btrfs: found 82 extents
btrfs: found 82 extents
btrfs: relocating block group 1873843060736 flags 9
btrfs: found 344 extents
btrfs: found 344 extents
btrfs: relocating block group 1871695577088 flags 9






-- 
http://magnatune.com - Music shared the way it should be.

Re: Strangeness on btrfs balance..

[Felix Blanke]

Hi,

balancing 1TB of data can take > 1 day. So I don't think there is something wrong
just because the third device got no io. Just wait some more hours.

I don't know how the balancing does his work, but it is possible that it first
balance throught the old devices and then add the new one or something like that.


Regards,
Felix


On 05. February 2011 - 03:31, Evert Vorster wrote:
> Date:	Sat, 5 Feb 2011 03:31:27 -0700
> From: Evert Vorster <evorster@gmail.com>
> To: linux-btrfs@vger.kernel.org
> Subject: Strangeness on btrfs balance..
> 
> Hi there...
> 
> I have kernel version 2.6.36.3, compiled with gcc 4.4.5, btrfstools
> version 0.19+20101101
> 
> I have a btrfs filesystem (/data) consisting of two 1TB hard disks, raid0.
> 
> I added in another 1TB hard drive.
> 
> root@X86-64:~# btrfs filesystem show
> failed to read /dev/sdh
> failed to read /dev/sdg
> failed to read /dev/sdf
> failed to read /dev/sde
> failed to read /dev/sr0
> failed to read /dev/fd0u800
> failed to read /dev/fd0
> Label: none  uuid: 91a3ca88-7883-45a1-b83d-d95bf98a1d51
>         Total devices 3 FS bytes used 1.20TB
>         devid    3 size 931.51GB used 0.00 path /dev/sdb
>         devid    1 size 931.51GB used 889.15GB path /dev/sdc
>         devid    2 size 931.51GB used 889.13GB path /dev/sdd
> 
> Btrfs Btrfs v0.19
> 
> Sat Feb 05 03:22:29
> root@X86-64:~#
> ----------------------------------------------------
> So, I want to balance my data across these three devices, but I
> noticed an inconsistencybteween "man btrfs" and btrfs' help...
> 
> root@X86-64:~# man btrfs | grep balance
>        btrfs device balance <path>
>        device balance <path>
> 
> Sat Feb 05 03:23:50
> 
> and
> 
> Sat Feb 05 03:24:19
> root@X86-64:~# btrfs | grep balance
>         btrfs filesystem balance <path>
> 
> Sat Feb 05 03:24:20
> 
> According to the man page, to balance a filesystem, the command is:
> btrfs device balance <path>
> In my case: btrfs device balance /data
> This returns an error:
> 
> root@X86-64:~# btrfs device balance /data
> ERROR: unknown command 'device'
> 
> When I try with
> btrfs filesystem balance /data, I can see data being read and written
> to the two original disks, but the new disk is not getting written to.
> I keep an eye on disk IO with gkrellm. Also, after about an hour of
> balancing, /dev/sdb is still completely empty.
> 
> Any idea of why this is happening?
> Last few lines of dmesg:
> floppy0: disk absent or changed during operation
> end_request: I/O error, dev fd0, sector 128
> end_request: I/O error, dev fd0, sector 0
> btrfs: found 69 extents
> btrfs: relocating block group 1897465380864 flags 9
> btrfs: found 95 extents
> btrfs: found 95 extents
> btrfs: relocating block group 1895317897216 flags 9
> btrfs: found 81 extents
> btrfs: found 81 extents
> btrfs: relocating block group 1893170413568 flags 9
> btrfs: found 93 extents
> btrfs: found 93 extents
> btrfs: relocating block group 1891022929920 flags 9
> btrfs: found 96 extents
> btrfs: found 96 extents
> btrfs: relocating block group 1888875446272 flags 9
> btrfs: found 93 extents
> btrfs: found 93 extents
> btrfs: relocating block group 1886727962624 flags 9
> btrfs: found 90 extents
> btrfs: found 90 extents
> btrfs: relocating block group 1884580478976 flags 9
> btrfs: found 99 extents
> btrfs: found 99 extents
> btrfs: relocating block group 1882432995328 flags 9
> btrfs: found 1 extents
> btrfs: found 1 extents
> btrfs: relocating block group 1880285511680 flags 9
> btrfs: found 101 extents
> btrfs: found 101 extents
> btrfs: relocating block group 1878138028032 flags 9
> btrfs: found 105 extents
> btrfs: found 105 extents
> btrfs: relocating block group 1875990544384 flags 9
> btrfs: found 82 extents
> btrfs: found 82 extents
> btrfs: relocating block group 1873843060736 flags 9
> btrfs: found 344 extents
> btrfs: found 344 extents
> btrfs: relocating block group 1871695577088 flags 9
> 
> 
> 
> 
> 
> 
> -- 
> http://magnatune.com - Music shared the way it should be.
> --
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---end quoted text---

Re: Strangeness on btrfs balance..

[Helmut Hullen]

Hallo, Evert,

Du meintest am 05.02.11:

> I have kernel version 2.6.36.3, compiled with gcc 4.4.5, btrfstools
> version 0.19+20101101

> I have a btrfs filesystem (/data) consisting of two 1TB hard disks,
> raid0.

> I added in another 1TB hard drive.

> root@X86-64:~# btrfs filesystem show
> failed to read /dev/sdh
> failed to read /dev/sdg
> failed to read /dev/sdf
> failed to read /dev/sde
> failed to read /dev/sr0
> failed to read /dev/fd0u800
> failed to read /dev/fd0

That's a "well known" error; the fix isn't yet implemented.

> Any idea of why this is happening?
> Last few lines of dmesg:
> floppy0: disk absent or changed during operation
> end_request: I/O error, dev fd0, sector 128
> end_request: I/O error, dev fd0, sector 0

May be that's another "well known" error; there is a fix too ...


> btrfs: found 69 extents
> btrfs: relocating block group 1897465380864 flags 9
> btrfs: found 95 extents
> btrfs: found 95 extents
> btrfs: relocating block group 1895317897216 flags 9
> btrfs: found 81 extents
> btrfs: found 81 extents

Just wait some time.
When I remember correctly: the "relocating" message appears every minute  
(slightly rounded).
In your example there's a difference of about 1/1000, you have to wait  
about 1000 minutes.

Viele Gruesse!
Helmut