labelling

labelling

[Helmut Hullen]

Hallo, linux-btrfs,

I have problems with btrfs labels.

My way:

2-TByte-disk:

        mkfs.btrs LABEL=MM2 /dev/sdd2

worked.
Mounting "mount LABEL=MM2 /srv/MM" worked.

Additional 1.5-TByte-Disk:

        btrfs add device /dev/sdc3 /srv/MM
        ... balance ...

worked.

        findfs LABEL=MM2

shows "/dev/sdd2" (the first partition)

        file -s /dev/sdd2
        file -s /dev/sdc3

shows "LABEL=MM2" for both partitions (that's not good).

Unmounting "/srv/MM" and

        mount LABEL=MM2 /srv/MM

doesn't work now, it tries to mount /dev/sdd2 and mourns.

        mount /dev/sdd2 /srv/MM

shows the same error message,

        mount /dev/sdc3 /srv/MM

(mounting the added partition) works fine, the whole space is available.

But what can I do with the 2 identical labels? How can I delete (or  
change) the label of the first btrfs partition?

----------------------------

By the way:

"df" shows about 3.4 TByte usable space (2 TByte and 1.5 TByte), but

        btrfs filesystem df /srv/MM

tells

        Data: total=2.70TB, used=1.64TB

I'm missing about 0.7 TByte!

Viele Gruesse!
Helmut

Re: labelling

[Hugo Mills]

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On Wed, Nov 10, 2010 at 08:40:00AM +0100, Helmut Hullen wrote:
> Hallo, linux-btrfs,
> 
> I have problems with btrfs labels.
> 
> My way:
> 
> 2-TByte-disk:
> 
>         mkfs.btrs LABEL=MM2 /dev/sdd2
> 
> worked.
> Mounting "mount LABEL=MM2 /srv/MM" worked.
> 
> Additional 1.5-TByte-Disk:
> 
>         btrfs add device /dev/sdc3 /srv/MM
>         ... balance ...
> 
> worked.
> 
>         findfs LABEL=MM2
> 
> shows "/dev/sdd2" (the first partition)
> 
>         file -s /dev/sdd2
>         file -s /dev/sdc3
> 
> shows "LABEL=MM2" for both partitions (that's not good).

   No, this is both good and correct. You've got a single filesystem
spanning multiple block devices. The *filesystem* possesses the label,
and with btrfs you can mount the filesystem using *any* of the block
devices that compose it, so both block devices should indeed show the
FS label, which is what's happening here.

> Unmounting "/srv/MM" and
> 
>         mount LABEL=MM2 /srv/MM
> 
> doesn't work now, it tries to mount /dev/sdd2 and mourns.
> 
>         mount /dev/sdd2 /srv/MM
> 
> shows the same error message,

   What's the error message? What do you get in your kernel logs when
you do this? This should work, so there's something wrong, but it's
(probably) not to do with disk labels.

>         mount /dev/sdc3 /srv/MM
> 
> (mounting the added partition) works fine, the whole space is available.
> 
> But what can I do with the 2 identical labels? How can I delete (or  
> change) the label of the first btrfs partition?

   You can't, as I explained above.

> ----------------------------
> 
> By the way:
> 
> "df" shows about 3.4 TByte usable space (2 TByte and 1.5 TByte), but
> 
>         btrfs filesystem df /srv/MM
> 
> tells
> 
>         Data: total=2.70TB, used=1.64TB
> 
> I'm missing about 0.7 TByte!

   In "btrfs filesystem df", the "total" field is the space that has
been allocated to block groups. As more space is needed on the
filesystem, the "total" field will increase to use up the additional
raw storage (if you're using RAID1 or RAID10, this will be at a ratio
of 2:1; with RAID0 or simple allocation, the ratio is 1:1).

   Hugo.

-- 
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      --- In event of Last Trump,  please form an orderly queue ---      
                          and await judgement.                           

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Re: labelling

[Helmut Hullen]

Hallo, Hugo,

Du meintest am 10.11.10:

>>         findfs LABEL=MM2
>>
>> shows "/dev/sdd2" (the first partition)
>>
>>         file -s /dev/sdd2
>>         file -s /dev/sdc3
>>
>> shows "LABEL=MM2" for both partitions (that's not good).

>    No, this is both good and correct. You've got a single filesystem
> spanning multiple block devices. The *filesystem* possesses the
> label, and with btrfs you can mount the filesystem using *any* of the
> block devices that compose it, so both block devices should indeed
> show the FS label, which is what's happening here.

>> Unmounting "/srv/MM" and
>>
>>         mount LABEL=MM2 /srv/MM
>>
>> doesn't work now, it tries to mount /dev/sdd2 and mourns.
>>
>>         mount /dev/sdd2 /srv/MM
>>
>> shows the same error message,

>    What's the error message? What do you get in your kernel logs when
> you do this? This should work, so there's something wrong, but it's
> (probably) not to do with disk labels.

I'll tell tomorrow; the system is just copying more than 1 TByte ...

>> ----------------------------
>>
>> By the way:
>>
>> "df" shows about 3.4 TByte usable space (2 TByte and 1.5 TByte), but
>>
>>         btrfs filesystem df /srv/MM
>>
>> tells
>>
>>         Data: total=2.70TB, used=1.64TB
>>
>> I'm missing about 0.7 TByte!

>    In "btrfs filesystem df", the "total" field is the space that has
> been allocated to block groups. As more space is needed on the
> filesystem, the "total" field will increase to use up the additional
> raw storage

Ok - and many thanks! I'll see tomorrow ...

Viele Gruesse!
Helmut

Re: labelling

[Helmut Hullen]

Hallo, Hugo,

Du meintest am 10.11.10:

>>         findfs LABEL=MM2
>>
>> shows "/dev/sdd2" (the first partition)
>>
>>         file -s /dev/sdd2
>>         file -s /dev/sdc3
>>
>> shows "LABEL=MM2" for both partitions

[...]

>> Unmounting "/srv/MM" and
>>
>>         mount LABEL=MM2 /srv/MM
>>
>> doesn't work now, it tries to mount /dev/sdd2 and mourns.

>    What's the error message? What do you get in your kernel logs when
> you do this? This should work, so there's something wrong, but it's
> (probably) not to do with disk labels.

Strange - very strange ...

Today in the morning it didn't work. Now it works.

I'll see tomorrow if this strange behaviour is related somehow to cold  
start or some other commands before invoking "mount".

Viele Gruesse!
Helmut

Re: labelling

[Helmut Hullen]

Hallo, Hugo,

Du meintest am 10.11.10:

>>         findfs LABEL=MM2
>>
>> shows "/dev/sdd2" (the first partition)
>>
>>         file -s /dev/sdd2
>>         file -s /dev/sdc3
>>
>> shows "LABEL=MM2" for both partitions

>>         mount LABEL=MM2 /srv/MM
>>
>> doesn't work now, it tries to mount /dev/sdd2 and mourns.
>>
>>         mount /dev/sdd2 /srv/MM
>>
>> shows the same error message,

# mount LABEL=MM2
mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

# mount /dev/sdd2
mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

>    What's the error message? What do you get in your kernel logs when
> you do this? This should work, so there's something wrong, but it's
> (probably) not to do with disk labels.

>>         mount /dev/sdc3 /srv/MM
>>
>> (mounting the added partition) works fine, the whole space is
>> available.

That's the behaviour after a cold boot.

        umount /srv/MM
        mount LABEL=MM2 /srv/MM

then works.
Only the first try with LABEL or with "the other" device seems to fail.

I don't like testing via reboot ...

Viele Gruesse!
Helmut

Re: labelling

[Tsutomu Itoh]

Hi.

(2010/11/11 16:48), Helmut Hullen wrote:
> Hallo, Hugo,
>
> Du meintest am 10.11.10:
>
>>>          findfs LABEL=MM2
>>>
>>> shows "/dev/sdd2" (the first partition)
>>>
>>>          file -s /dev/sdd2
>>>          file -s /dev/sdc3
>>>
>>> shows "LABEL=MM2" for both partitions
>
>>>          mount LABEL=MM2 /srv/MM
>>>
>>> doesn't work now, it tries to mount /dev/sdd2 and mourns.
>>>
>>>          mount /dev/sdd2 /srv/MM
>>>
>>> shows the same error message,
>
> # mount LABEL=MM2
> mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
>         missing codepage or helper program, or other error
>         In some cases useful info is found in syslog - try
>         dmesg | tail  or so
>
> # mount /dev/sdd2
> mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
>         missing codepage or helper program, or other error
>         In some cases useful info is found in syslog - try
>         dmesg | tail  or so
>
>>     What's the error message? What do you get in your kernel logs when
>> you do this? This should work, so there's something wrong, but it's
>> (probably) not to do with disk labels.
>
>>>          mount /dev/sdc3 /srv/MM
>>>
>>> (mounting the added partition) works fine, the whole space is
>>> available.
>
> That's the behaviour after a cold boot.
>
>          umount /srv/MM
>          mount LABEL=MM2 /srv/MM
>
> then works.
> Only the first try with LABEL or with "the other" device seems to fail.

I encountered the same problem, too.
Please try 'btrfsctl -a' before mounting.

Thanks.
Itoh

Re: labelling

[Felix Blanke]

Am Thu, 11 Nov 2010 17:37:38 +0900
schrieb Tsutomu Itoh <t-itoh@jp.fujitsu.com>:

> Hi.
> 
> (2010/11/11 16:48), Helmut Hullen wrote:
> > Hallo, Hugo,
> >
> > Du meintest am 10.11.10:
> >
> >>>          findfs LABEL=MM2
> >>>
> >>> shows "/dev/sdd2" (the first partition)
> >>>
> >>>          file -s /dev/sdd2
> >>>          file -s /dev/sdc3
> >>>
> >>> shows "LABEL=MM2" for both partitions
> >
> >>>          mount LABEL=MM2 /srv/MM
> >>>
> >>> doesn't work now, it tries to mount /dev/sdd2 and mourns.
> >>>
> >>>          mount /dev/sdd2 /srv/MM
> >>>
> >>> shows the same error message,
> >
> > # mount LABEL=MM2
> > mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
> >         missing codepage or helper program, or other error
> >         In some cases useful info is found in syslog - try
> >         dmesg | tail  or so
> >
> > # mount /dev/sdd2
> > mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
> >         missing codepage or helper program, or other error
> >         In some cases useful info is found in syslog - try
> >         dmesg | tail  or so
> >
> >>     What's the error message? What do you get in your kernel logs
> >> when you do this? This should work, so there's something wrong,
> >> but it's (probably) not to do with disk labels.
> >
> >>>          mount /dev/sdc3 /srv/MM
> >>>
> >>> (mounting the added partition) works fine, the whole space is
> >>> available.
> >
> > That's the behaviour after a cold boot.
> >
> >          umount /srv/MM
> >          mount LABEL=MM2 /srv/MM
> >
> > then works.
> > Only the first try with LABEL or with "the other" device seems to
> > fail.
> 
> I encountered the same problem, too.
> Please try 'btrfsctl -a' before mounting.
> 
> Thanks.
> Itoh

btrfsctl is deprecated.

Please use "btrfs device scan" instead.


Regards,
Felix


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Re: labelling

[Helmut Hullen]

Hallo, Tsutomu,

Du meintest am 11.11.10:

[cold start]

>> # mount LABEL=MM2
>> mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
>>         missing codepage or helper program, or other error
>>         In some cases useful info is found in syslog - try
>>         dmesg | tail  or so

> I encountered the same problem, too.
> Please try 'btrfsctl -a' before mounting.

It works - thank you!

Another problem (I had mentioned it some days before):

        btrfsctl -a

tests every block device in "/dev". And as I don't use "udev" there are  
many device entries without an existing devices (p.e. hda1 to hda31).  
"btrfsctl" should use something like "/proc/partitions" to test only  
existing devices.

I have to call

        /sbin/btrfsctl -a 2>/dev/null

to make the output readable, and suppressing error messages is no good  
style.

Viele Gruesse!
Helmut

Re: labelling

[Helmut Hullen]

Hallo, Tsutomu,

Du meintest am 11.11.10:

>>>>          mount LABEL=MM2 /srv/MM
>>>>
>>>> doesn't work now, it tries to mount /dev/sdd2 and mourns.
>>>>
>>>>          mount /dev/sdd2 /srv/MM
>>>>
>>>> shows the same error message,


> I encountered the same problem, too.
> Please try 'btrfsctl -a' before mounting.

This command (or "/sbin/btrfs device scan 2>/dev/null") has to be put  
into the "init" procedure; it may be needed in runlevel 1 too, it may be  
needed if the root partition is a btrfs partition.

In my homemade slackware/sysv installation I have put this command into  
"/etc/init.d/boot", maybe for slackware it has to be put into "/etc/ 
rc.d/rc.S".

Viele Gruesse!
Helmut