fsck with "err is 1"

fsck with "err is 1"

[Blair Zajac]

Hello,

I'm trying btrfs in a VirtualBox VM running Ubuntu 11.10 with kernel 3.0.0.  Running fsck I get a message with "err is 1".

root@ubuntu-11-10-i386:/# fsck -v -v /
fsck from util-linux 2.19.1
root 257 inode 878 errors 400
found 6938783744 bytes used err is 1
total csum bytes: 6281436
total tree bytes: 501153792
total fs tree bytes: 465928192
btree space waste bytes: 134778274
file data blocks allocated: 12274962432
 referenced 6405234688
Btrfs Btrfs v0.19

Does this mean there's an error?  Is err either always 0 or 1, or does err increment beyond 1?

I've tried doing the following to fix the filesystem, but "err is 1" doesn't change.

- btrfs filesystem balance /
- find / -mount -type f -print0 | xargs -0 cat >/dev/null

The later shows no errors in dmesg.

Thanks,
Blair

Re: fsck with "err is 1"

[Fajar A. Nugraha]

On Wed, Nov 23, 2011 at 12:33 PM, Blair Zajac <blair@orcaware.com> wrot=
e:
> Hello,
>
> I'm trying btrfs in a VirtualBox VM running Ubuntu 11.10 with kernel =
3.0.0. =A0Running fsck I get a message with "err is 1".

> Does this mean there's an error? =A0Is err either always 0 or 1, or d=
oes err increment beyond 1?

I can't answer that, but I can tell you that fsck for btrfs right now
is almost useless. It can't fix anyting.

Short summary, if you can mount the fs, and can access the data, and
don't have any weird messages on syslog, then it's most likely OK.

--=20
=46ajar
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Re: fsck with "err is 1"

[Blair Zajac]

On Nov 22, 2011, at 10:02 PM, Fajar A. Nugraha wrote:

> On Wed, Nov 23, 2011 at 12:33 PM, Blair Zajac <blair@orcaware.com> wrote:
>> Hello,
>> 
>> I'm trying btrfs in a VirtualBox VM running Ubuntu 11.10 with kernel 3.0.0.  Running fsck I get a message with "err is 1".
> 
>> Does this mean there's an error?  Is err either always 0 or 1, or does err increment beyond 1?
> 
> I can't answer that, but I can tell you that fsck for btrfs right now
> is almost useless. It can't fix anyting.

Thank you, I've read that fsck doesn't fix anything.  I was curious if doing the scrub would resolve it.

Blair

Re: fsck with "err is 1"

[Helmut Hullen]

Hallo, Blair,

Du meintest am 23.11.11:

>> I can't answer that, but I can tell you that fsck for btrfs right
>> now is almost useless. It can't fix anyting.

> Thank you, I've read that fsck doesn't fix anything.  I was curious
> if doing the scrub would resolve it.

I had tried ... about 4 Tbyte data have gone.

3 disks bundled with data=raid0, metadata=raid1.

One disk had problems, before I run "scrub" I could read most files,  
Running "scrub": all had gone.

One big problem of btrfs seems to be: you can't see on which partition/ 
disk the defect sector (or something else) may be, if there is 1 error  
in 1 partition you have to restore the complete bundle of disks/ 
partitions.

Yes - I know: btrfs is still under construction.

In my special case: the 4 TByte are a kind of video archive. No  
"valuable" data, only "nice to have". And old people still know the  
behaviour of old 35 mm film and/or VHS cassettes: they have errors. But  
these errors don't damage the whole archive.

Viele Gruesse!
Helmut

Re: fsck with "err is 1"

[Jan Schmidt]

On 23.11.2011 18:32, Helmut Hullen wrote:
> One big problem of btrfs seems to be: you can't see on which partition/ 
> disk the defect sector (or something else) may be

A recent kernel (3.2, still rc) will tell you the byte number when an
error occurs, and also give the the opportunity to resolve this address
to all files affected.

-Jan

Re: fsck with "err is 1"

[Helmut Hullen]

Hallo, Jan,

Du meintest am 23.11.11:

>> One big problem of btrfs seems to be: you can't see on which
>> partition/ disk the defect sector (or something else) may be

> A recent kernel (3.2, still rc) will tell you the byte number when an
> error occurs, and also give the the opportunity to resolve this
> address to all files affected.

May be. I had used the brand new kernel 3.1.

btrfs may be fine when it works as proposed. It's still under heavy  
construction.

I had to rebuild my 4-TByte archive the second time within 1 year -  
that's no reliable system.

May be the situation for really big bundles of disk gets better when  
something like raid 5 does work. I'll wait.

Viele Gruesse!
Helmut