News from SRM v2.2 workshop at CERN on 28 Aug

• Trunov, Artem (IN2P3)

http://agenda.cern.ch/fullAgenda.php?ida=a063257

Discussion

• all

* Tape1Disk[01] classes Kors - is there "double counting" for Tape1Disk0 and Tape1Disk1 classes? Artem - no. It could be a common space or separate space, but no double counting and data replication. * Transition Tape0 -> Tape1 Kors - problem for SARA. Artem- It's a problem for many systems. LHCb has a use case - want to store the data they produces during release validation (or delete it without storing to tape). But it seems that using this class can be avoided by LHCb, either by using Tape1Disk1 class right away, or using Tape0Disk1 and then physically copying data again using Tape1Disk1 class. Jos - Do experiments foresee deletion from tape? Artem - normally no, but sometime. Kors - SARA never deleted experiment's data in 30 years. Hellen - FNAL only occasionally deletes data: either test data or invalidated data. Artem - BaBar also keeps even oldest MC data. Phisicist do need old data to compare SW performance etc. Jos - Who needs tobe responsible for deletion from tape - users or administrators? Hellen - At FANL filesare deleted from the namespace only, not actually from tape automatically. This allows admins to recover the data in case a user made a mistake. Lionel - At IN2P3 files will be deleted from tape automatically, no recovery is supported. Users may use different backup service is possibility for recovery is desired. Files deleted in dCache also get deleted from HPSS automatically. Jos - It must be a site choice * Discussion on tape vs. disk Jos - No one should think that "custodial data" on tape is more secure than on disk. Hellen - Files get lost on tape rearly. Also tape storage vendor can recover some files on tapes, reducing the loss even further. Artem - experiments will replicate data on tape, most of them will have two custodial locations for each data file. Kors - Tape is still cheaper and easier to deal with for permanent storage. Jos - yes, managing disk is more complex, but experiments could still consider tape vs. disk. * variouse topics Artem - do our meetings bring better understanding of SRM, storageclasses, experiments' reqiurements? Kors - people do become aware of problems :) Kors - Ownership during the class transition? Will it change? Artem - Should not. Transitions will be permitted to the owneronly? To confirm with deleopers. Artem - Next meeting? Most likely during the week of Sep 18 Kors - will talk to Roger Jones from Atlas and invite him to present Atlas storage.