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I would be surprised if a knowledgible person in ATLAS had made this statement. As I can't be bothered reading their TDR in full I am copying in Roger Jones for his comments. I have glanced through it and find the following requirements for a Tier2 (I include the whole list for interest) - Medium- or long-term storage for required samples. For analysis work these will be mostly AOD but could include some fraction of ESD or RAW data for more detailed studies. - Transfer, buffering and short-term caching of relevant data from Tier-1 and transfer of produced data to Tier-1 for storage. - Provision and management of local temporary working space for analysis, calibration of development tasks. - Database services in agreement with the ATLAS DDM strategy. - Prioritization of access to data and computing resources. - Accounting for processing and data storage. - Publication of the necessary information to be used by the Grid services and the ATLAS Production System. To me, the first three seem relevant. If the fourth implied database backup I would expect it to be a dedicated system and not a general purpose SE. Medium and long-term storage seems consistent with my understanding of 'permanent' without implying any quality or guarantee of service. In contrast the ATLAS description of a Tier1 includes the requirement - In accepting data from Tier-2, a Tier-1 accepts to store them in a permanent and safe way and to provide access to it in agreement with current ATLAS policy. This is true for both simulated and derived data. This seems fairly clear to me, the ATLAS model recognises different levels of storage quality and identifies them in T2 and T1. Worth talking further with them as to whether they expect these differences to be published in the information service. John > -----Original Message----- > From: Testbed Support for GridPP member institutes > [mailto:[log in to unmask]] On Behalf Of Simon George > Sent: 06 October 2005 13:30 > To: [log in to unmask] > Subject: Re: Reminder of the next UKI meeting - Wednesday 5th > October 11:00-12:00 via VRVS > > Hi John, > > I also had the impression from the discussion with ATLAS a > while ago that they were surprised that our SEs could not be > regarded as permanent, high quality, backed up storage. And I > also drew the conclusion (as I think did everyone in London > Tier2) that the recommended way to flag a SE which is not > backed up and could go down for a long time if there was a > failure (due to limited manpower at the site) was "volatile". > If several of us thought this then there must be something in > it, even if it is misguided. > > To answer you Q: we don't think our SEs are less reliable > than everyone else's. Rather, we think other people are are > not necessarily advertising the true nature of their site. A > Tier1 SE is so different to what a Tier2 site can provide. > Some sites my have better support and facilities than others. > > btw This was in addition to the discussion with ATLAS about > whether sites could delete old files. > > I think we do need ways to distinguish between the differing > qualities of SEs. I know for ATLAS, long term availability > and uptime are important factors. Disk vs tape (access time) > is also important. The way forward should be a quick > discussion between sites and experiments of how they would > like SEs to be described, then update the Glue Schema, > document it and we will fill it in. If there is no forum for > this, please set one up! > > Cheers, > Simon > > -------------------------------------------------------------- > ------------- > Simon George, Dept of Physics, Royal Holloway college, > University of London > Email [log in to unmask] Tel. +44 1784 41 41 85 Fax. > +44 1784 472794 > > On Thu, 6 Oct 2005, Gordon, JC (John) wrote: > > > Would either of you care to spell out why you think your > systems are > > more unsafe than everyone else's? > > > > John > > > > > -----Original Message----- > > > From: Testbed Support for GridPP member institutes > > > [mailto:[log in to unmask]] On Behalf Of William Hay > > > Sent: 06 October 2005 12:36 > > > To: [log in to unmask] > > > Subject: Re: Reminder of the next UKI meeting - Wednesday 5th > > > October 11:00-12:00 via VRVS > > > > > > > Hi John, > > > > > > > > I have declared my storage 'volatile' and I've done so not > > > because I > > > > delete files whenever I feel like but because I don't > consider my > > > > storage safe enough to be declared permanent and if > > > something happens > > > > I know I've done my duty warning the experiments in advance. If > > > > experiments don't exploit the glue schema they should. > > > That's why we > > > > have an information system. > > > > > > > > cheers > > > > alessandra > > > > > > Ditto. > > > > > > William Hay, UCL-CCC Site Administrator, Information Systems, > > > EISD,UCL > > > > > >