[glue-wg] Datastore proposal

[Maarten.Litmaath at cern.ch]

On Thu, 17 Apr 2008, Burke, S (Stephen) wrote:

> > Can we collapse the tape with the cache into a single 
> > Datastore that has both an Online and a Nearline component?
> 
> I would say not, the basic idea of a Datastore is to make it
> homogeneous. Is there a real problem with having a many-to-many relation
> between Share and Datastore? In LDAP I think it's OK, you just put

No, I do not have a problem with that.  My point is that the very same
facility that provides the tape may at the same time control the disk:
the disk would just be the online component of the tape store, and not
something that one has to foresee separately, if desired.

In principle a tape store does not _have_ to have disk (e.g. central data
recording in CASTOR-1 could write directly to tape), but if it has disk,
that disk is directly managed by the same software that manages the tape,
so I felt we might want to express that explicitly by putting an online
component alongside the nearline component of the DataStore.