[glue-wg] Suggestion for splitting the StorageShare.

[Owen Synge]

On Mon, 28 Apr 2008 17:36:49 +0100
"Burke, S (Stephen)" <S.Burke at rl.ac.uk> wrote:

> Paul Millar [mailto:paul.millar at desy.de] said:
> > Moreover, the ACL semantics will (in general) be filesystem-specific.

Hello Steven,
 
> Well, in the medium term I think the implementations will have to
> converge on a common authorisation model,

I hope so, but cannot see a reason why this as a desire, should be
driven by Glue. It is definitely not a requirement for Glue to be
useful. The desire though is noble provided it is practical as it may
make grid end user application development easier.

Why will Glue be less useful if it does not include these details?

> or at least allow a grid like
> WLCG to have a common profile which gives the same behaviour at all
> sites. However, we seem to be quite a way from that at the moment, and
> the recent decision seems to be that we back off from that and approach
> it from a different angle.
> 
> > The point isn't what you or I might think of as "correct" 
> > behaviour, just that 
> > different people (and different filesystems) will interpret 
> > these questions differently.
> 
> Err, yes - and if it is like that (as often seems to be the case in the
> grid world) it will be totally unusable in practice! 

Here I disagree, We have abstraction as our friend here, Grid
catalogues and FTS allow data to be transferred.

Can you explain why expressing ACL's is a requirement for Glue?

> (Cue another couple
> of years of Flavia's tests to get everything to have consistent
> behaviour ...)
> 
> Stephen

Since 2/3 of the storage of the wLCG grid is stored in dCache, and 100%
of NorduGrid and OSG is mostly represented dCache which will support a
standard ACL, I do not believe Glue is enhanced by ignoring the use
cases such as representing Castor and DPM which make up 1/3 of Glue
storage in wLCG, as this is a significant minority, so we should not
publish ACL's particularly since the grid has moved on (FOC and pilot
jobs) and further markup can be provided for VO's outside the Glue
schema for using the legacy of a wLCG interpretation of ACL's.

I see no problem with experiments working around the differences of
minority storage services such as Castor (with so few deployments it
cannot be the other way around), provided the implementation and
version can be discovered.

Expecting Castor and DPM to change their getting and setting ACL model
at this stage of development just to be pure in our Glue implementation
I think is a bad idea.

Regards

Owen Synge