Terms - Proposals

[Clive Page]

On Fri, 10 Dec 2004, Martin @ ROE wrote:

> >> data centre (or center)
>
> A center where data is kept :-) A physical location with a defined team
> that hold and manage published data.  For example, the ROE WFCAM
> datacenter.  The OpenSky Portal.  VizieR.  Might often be the same as
> 'site' where a site has only one datacenter.

My interpretation is that a data centre was the same as a site - e.g. that
CDS is a data centre, with Vizier, Aladin, Simbad etc as separate data
collections (= datasets?) within it.

> >>database
>
> The storage medium.  A database might be SQL Server, or a collection of
> FITS files.

In the DBMS world the term database has a fairly clear meaning as a
collection of relations (tables) which can be related to one another.  To
continue the above examples, Vizier is a also a database, as one can
submit single queries that search one or more of its tables.  A single
DBMS (such as Oracle) is sometimes set up to manage more than one
database, as you may want to keep them separate (e.g. one database public
and one private).

> >>mirror
> >>copy

I think I agree with your subsequent message: a copy is a snapshot which
may later diverge from the original if the original changes; a mirrored
copy is an attempt to have an actively managed replica, so that (apart
from temporary differences pending resynchronisation) the two versions are
always identical.

But that's just my 2 cents worth.

-- 
Clive Page
Dept of Physics & Astronomy,
University of Leicester,
Leicester, LE1 7RH,  U.K.