[Lustre-devel] How store HSM metadata in MDT

[Eric Barton]

> For Lustre HSM project, it will be needed to store, for each file, a 
> list of information describing how many copies the file has in the HSM, 
> what is their HSM ID, the copy date, and so on. This data could easily 
> reach 500 bytes (I think we will need between 40 and 50 bytes per HSM 
> copy, and we should be able to save at least 10 copies, surely more).
> The question is: where could we store this data on MDT, in which place 
> (EA?) and how manage this.

Storing information about > 1 HSM copy violates one of our groundrules...

> 3. The file system only has attributes to indicate the state of the primary
> archived copy (probably the last fully archived copy of the file), and can
> retrieve that file on demand (without user intervention).

    Cheers,
              Eric