Subject: Re: RFC: new mode bits in stat structure
To: Ted Lemon <>
From: Matthew Jacob <>
List: tech-kern
Date: 06/26/1998 10:47:53
Ted Lemon wrote:
> > 1) The flag bits method is not truly heirarchical.  It only allows a
> >    2-level storage system.
> Why not?   Let's say you have a three-layer storage scheme.   If the
> file has been archived on layer 1, then you go to layer 2. 

That is essentially what NAStore does. Especially the one in process
NAStore-2 was 2-level. If the file wasn't resident, go the RASH database
to find out which tape volume it's on. NAStore-3 has further indirection
in that if the file isn't resident in the filesystem, it may be in a
Virtual Volume (which may or may not be on disk) so go to the VVM
to find out if that VVM has been staged to tape or not. If tape, get
the tape. And so on.