Re: xfs_repair of critical volume

Eli Morris
2010-11-30T07:21:05Z

On Nov 16, 2010, at 11:47 PM, Dave Chinner wrote:

> On Tue, Nov 16, 2010 at 11:29:41PM -0800, Eli Morris wrote:
>> Hi Dave,
>>
>> Thanks a lot for your help. I looked at the man page and elsewhere for this info and can't find what this means:
>>
>>
>> extent: [startoffset..endoffset]: startblock..endblock
>>
>>
>> I understand what an offset would be, but what the heck is a startoffset and an endoffset?
>
> startoffset: file offset of the start of the extent
> endoffset: file offset of the end of the extent
>
>> Is the formula for the location of the file:
>>
>> startoffset + startblock through endoffset + endblock, where the blocks and the offsets are in 512 bytes?
>
> no.
>
>> So this file:
>>
>> 0: [0..1053271]: 5200578944..5201632215
>>
>> would be contained from:
>>
>> beginning: (0 + 5200578944) * 512 bytes
>> ending: (1053271 + 5201632215) * 512 bytes
>
> No, it translates like this:
>
> Logical Physical
> File Offset (bytes) block on disk
> ------------------- -------------
> 0 (0..511) 5200578944
> 1 (512..1023) 5200578945
> 2 (1024..1536) 5200578946
> ..... .....
> 1053270 5201632214
> 1053271 5201632215
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@fromorbit.com

Hi Dave,

Thanks for your help with this. I wrote the program and ran it through and it looks like we have we able to preserve 44 TB of valid data, while removing the corrupted files, which is a great result, considering the circumstances.

Thanks again,

Eli