Re: [Moosefs-users] Lost all metadata on master w/ full disk

[Michał B. <mic...@ge...>]

Hi Davies!

Sorry for the late reply but only now we had time to investigate your patch.
The change will be implemented in one of the upcoming releases. We didn't
use your patch in the exact shape you sent but we were highly inspired by it
:) So again - thank you very much for your commitment!


Kind regards
Michał 


-----Original Message-----
From: Davies Liu [mailto:dav...@gm...] 
Sent: Wednesday, November 09, 2011 6:32 AM
To: Nolan Eakins
Cc: moo...@li...
Subject: Re: [Moosefs-users] Lost all metadata on master w/ full disk

new patch, with bug fixed

On Tue, Nov 8, 2011 at 6:14 PM, Davies Liu <dav...@gm...> wrote:
> I have made a patch to solve this, at attached.
>
> On Tue, Nov 8, 2011 at 5:42 PM, Davies Liu <dav...@gm...> wrote:
>> In the mfsmaster, when dumping data to disk, it rename 
>> metadata.mfs.back to metadata.mfs.back.tmp first,  then write to 
>> metadata.mfs.back, finally, it unlink metadata.mfs.back.tmp and
metadata.mfs.
>>
>> If writing to metadata.mfs.back failed, we will get part of metadata, 
>> or damaged one, and previous metadata will be lost together.
>>
>> Why not writing to metadata.mfs.back.tmp first, if successfully, then 
>> rename it to metadata.mfs.back, and delete metadata.mfs ? I think this
way is much safer.
>>
>> In the metalogger, it does not check the downloaded metadata,  if it 
>> download a damaged one, then all the metadata will be lost. let 
>> metalogger keep sereral recently metadata may be safer.
>>
>> I will try to fix the above in my deployments, losing metadata is TOO 
>> UNACCEPTABLE.
>>
>> On Tue, Nov 8, 2011 at 7:24 AM, Nolan Eakins <no...@ea...> wrote:
>>> I have a little server setup to give MooseFS a try. This server ran 
>>> out of disk space on its root partition a day or two ago. This 
>>> partition is where mfsmaster stored all of its data. Needless to 
>>> say, mfsmaster did something dumb and zeroed out all the metadata 
>>> files under /var/lib/mfs. It even looks like the metadata logger on 
>>> another machine was affected since it didn't store anything recoverable.
>>>
>>> So my entire moosefs file tree is completely hosed now, all because 
>>> mfsmaster can't handle a full disk.
>>>
>>> Other than this, I've been happy with MooseFS.
>>>
>>> Regards,
>>> Nolan
>>>
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>>
>>
>>
>> --
>>  - Davies
>>
>
>
>
> --
>  - Davies
>



--
 - Davies