xfs
[Top] [All Lists]

Re: xfs_repair of critical volume

To: Eli Morris <ermorris@xxxxxxxx>
Subject: Re: xfs_repair of critical volume
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 17 Nov 2010 18:47:08 +1100
Cc: xfs@xxxxxxxxxxx
In-reply-to: <A219F774-E2D5-4CEB-AB2B-399F3053DFF9@xxxxxxxx>
References: <75C248E3-2C99-426E-AE7D-9EC543726796@xxxxxxxx> <4CCD3CE6.8060407@xxxxxxxxxxxxxxxxx> <864DA9C9-B4A4-4B6B-A901-A457E2B9F5A5@xxxxxxxx> <201011121422.28993@xxxxxx> <BE08758D-20B4-48F1-8BF7-FCD0341D38C2@xxxxxxxx> <20101114110559.GB22876@dastard> <87214B07-148B-4580-84F2-792266DE2C55@xxxxxxxx> <20101116000436.GG22876@dastard> <A219F774-E2D5-4CEB-AB2B-399F3053DFF9@xxxxxxxx>
User-agent: Mutt/1.5.20 (2009-06-14)
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@xxxxxxxxxxxxx

<Prev in Thread] Current Thread [Next in Thread>