[glue-wg] Comparison with CIM

[owen.synge at desy.de]

On Fri, 2 May 2008 02:33:20 +0200
<Maarten.Litmaath at cern.ch> wrote:

> Hi Owen,
> 
> > [...] leave out Castor and DPM due to the low
> > level of storage deployment they have compared to dCache.
> 
> Last time I checked there were some 130 DPM installations,
> compared to some 60 dCache and 7 CASTOR installations.
> 
> The amount of disk storage at the dCache T1 and T2 sites will
> be larger than that of CASTOR (T0, T1) and DPM (T2) combined,
> but not by a lot, maybe 60 vs. 40%.  For tape it is 50-50.
> 
> I would not call that low at all, certainly not w.r.t. GLUE:
> there the DPM sites supporting many VOs might well dominate!

Hello Maarten, 

even if Jamie Shears is wrong with his figures on relative storage
within wLCG (1/3 of grids within GLue) and I would be surprised since
he is the coordinator of wLCG (and he presented this figure in HEPIX
last year the 60% of wLCG storage is dCache)

The most important point is that we all agree that GLUE is not to drive
storage requirements through its representation of the system. 

(note representation not model)

Irrespective of which SRM implementation people prefure the problem does
not disappear just by arguing over ACL implementations . I hope you
accept my argument that other systems are significant?

I would suggest you all consider that wLCG should first agree on a
format before we try and put it in GLUE, I hope you agree?

We can all pick our own preferred standard, and our favourite
implementation, but this in no way effects anything as the outcome (can
we write or read) will always resolve to TRUE or FALSE for a given
operation, do you agree?

Since the outcome resolves to TRUE or FALSE and experiments store where
they write data, the experiment is better placed to store the resolved
value since this is both already stored and already expressed in a
standardised way, for example in FOC?

I am sorry but GLUE cannot be everything, I see it as an advertising
service, upon which other things can represent information. I hope
others also recognise the point of the FOC initiative, and if they do,
and still favor ACL's they should explain why they dont see it as part
of FOC?

Regards

Owen Synge