Re: Data Deduplication with the help of an online filesystem check

Chris Mason
2009-06-04T12:43:28Z

On Thu, Jun 04, 2009 at 02:03:50PM +0200, Thomas Glanzmann wrote:
> Chris,
>
> > It is a counter and a back reference. With Yan Zheng's new format
> > work, the limit is not 2^64.
>
> That means that there is one back reference for every use of the block?
> Where is this back reference stored? (I'm asking because if one back
> reference for every copy is stored, it can obviously not be allocated
> statically).

These are all stored in the extent allocation tree. There isn't exactly
a 1:1 mapping but it is effectively that.

-chris