thorpej@nas.nasa.gov (Jason Thorpe) writes:
> For the HSM we're building on NetBSD/alpha, I need a couple of additional
> mode bits to indicate two separate additional file states:
> 	- File has been archived
> 	- File is not resident on disk

Just a few quick observations.  

1) The flag bits method is not truly heirarchical.  It only allows a
   2-level storage system.

2) The mod-time, size etc. information of the disk and background
   storage can't both be presented as the same time.

When I think "heirarchical" my mental pricture is of something like
the union-filesystem with an arbitrary number of layers.  eg:

	layer-1:	ramfs
	layer-2:	disk
	layer-3:	tape

The stat structure would perhaps return a new integer field, the
filesytem layer-number that this stat structure element referred to.

-wolfgang
-- 
Wolfgang Rupprecht  		<wolfgang+gnus@spam.free.or.die.wsrcc.com>  
http://www.wsrcc.com/wolfgang/