Re: btrfsck out of memory for big fs

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2018/8/17 下午1:26, litaibaichina@gmail.com wrote:
> thanks Qu.
> I am runing 4.12.
> /# btrfs --version
> btrfs-progs v4.12
> 
> Do you think btrfsck can fix the fs issue ?

Nope, transid is pretty tricky especially for super old corruption.

>  Or we better backup data and re-do the fs ? 

I'd recommend to backup data asap.

Thanks,
Qu

> 
> ______________________________________________________________________________________________________________________________________________________________________
> From: Qu Wenruo
> Date: 2018-08-17 12:34
> To: litaibaichina@gmail.com; linux-btrfs@vger.kernel.org
> Subject: Re: btrfsck out of memory for big fs
>  
>  
> On 2018/8/17 上午10:44, litaibaichina@gmail.com wrote:
>> Hi Guys,
>>
>> I had a big btrfs on a md device,  it be mounted , but after a while it will become ready only:
>> # btrfs fi df /data/
>> Data, single: total=24.46TiB, used=24.46TiB
>> System, DUP: total=8.00MiB, used=2.59MiB
>> System, single: total=4.00MiB, used=0.00B
>> Metadata, DUP: total=81.00GiB, used=79.71GiB
>> Metadata, single: total=8.00MiB, used=0.00B
>> GlobalReserve, single: total=512.00MiB, used=264.28MiB
>>
>> # dmesg -T
>> [Thu Aug 16 18:16:31 2018] BTRFS error (device md127): parent transid verify failed on 26603622694912 wanted 185320 found 207817
>> [Thu Aug 16 18:16:31 2018] BTRFS error (device md127): parent transid verify failed on 26603622694912 wanted 185320 found 207817
>  
> Transaction id mismatch, normally this means some of the fs is already
> corrupted before.
>  
> And considering the transid gap, the corruption happened quite a long
> time ago.
>  
>> [Thu Aug 16 18:16:31 2018] BTRFS warning (device md127): Skipping commit of aborted transaction.
>> [Thu Aug 16 18:16:31 2018] BTRFS: error (device md127) in cleanup_transaction:1864: errno=-5 IO failure
>> [Thu Aug 16 18:16:31 2018] BTRFS info (device md127): forced readonly
>> [Thu Aug 16 18:16:31 2018] BTRFS info (device md127): delayed_refs has NO entry
>>
>> I want to use btrfsck to check it,  but it will OOM :
>> # btrfsck /dev/md127
>> Checking filesystem on /dev/md127
>> UUID: 6b87a52f-9a5f-4d03-b345-9d954c2ce259
>> checking extents
>> Killed
>>
>> I am trying to use lowmem mode,  but as I tried before, it may OOM too,    any ideas ?
>  
> This depends on which version you tried before.
>  
> Lowmem mode used to do partial lowmem and partial normal mode check, and
> normal mode caused the OOM.
>  
> Latest lowmem mode should not cause OOM, but please ger ready for the
> super long run time.
>  
> Thanks,
> Qu
>>
>> Thanks.
>>
>  
> 


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