Hi Grieg,
> -----Original Message-----
> From: GRIDPP2: Deployment and support of SRM and local
> storage management [mailto:[log in to unmask]] On
> Behalf Of Greig A Cowan
> Sent: 13 June 2006 14:35
> To: [log in to unmask]
> Subject: Re: Quotas for dCache/DPM
>
> Hi Kostas,
>
> > I can not see how someone can implement space reservation sensibly
> > without supporting quotas as well, for a Tier 0/1 it might be easy
> > to just setup extra pools for each reservation but this isn't an
> > option for us. I suspect that this is what they plan as a solution
> > until they have quotas working.
> >
> > The situation at the moment is really bad we can not really support
> > more than a few VOs without quotas. We can get away with it at the
> > moment because not many VOs really use a SE.
>
> So what you are saying is that IC-HEP will not be able to
> guarantee that
> you can meet your MoU targets (or monthly VO allocations) for
> VO storage
> unless you have quotas. Without quotas and in the case where you have
> multiple VOs sharing pools (in dCache) then a single VO can
> still use up
> all of the space.
>
> I think it is tru to say that all Tier-2s have VOs sharing
> pools because
> it is not efficient for them to have VO specific pools. They
> do not have
> the same level of resources as Tier-1s to simply add in extra
> pools as
> required.
It's also possible to be much more dynamic, it's much easier to change
quotas to reallocate space than it is to drain and reassign pools. So if
a VO comes to us to ask for extra space during some crunch period we
could conceivably allocate them some space for a month or so by changing
the quotas doing that with pools probably wouldn't be worth the effort.
In theory it could also be use to increase performace for VOs with small
amounts of storage since this could be more efficiently spead across
multiple servers/access points rather.
Yours,
Chris.
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