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Storage Update

Storage Update. Flavia Donno CERN/IT. Overview. Summary of the discussions on the SRM v2.2 Addendum to the Usage Agreement Some questions for the experiments. The experiments requirements. The goal of the SRM v2.2 Addendum is to provide answers to the following Main questions :

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Storage Update

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  1. Storage Update Flavia Donno CERN/IT WLCG Grid Deployment Board CERN, 14 May 2008

  2. Overview • Summary of the discussions on the SRM v2.2 Addendum to the Usage Agreement • Some questions for the experiments WLCG Grid Deployment Board, CERN 13 May 2008

  3. The experiments requirements • The goal of the SRM v2.2 Addendum is to provide answers to the following • Main questions : • What kind of spaces (T1D0, T1D1, T0D1) • Space protection • Space selection • Pre-staging • Space usage statistics • Tape optimization (reducing the number of mount operations, etc.) • Main dates: • 19 May: technical agreement among the developers • 23 May: experiment agreement. Document submitted to a few site representatives for comments. • 2 June: document finalization with time estimation for implementation. • 10 June: submission to the MB for approval. Start of the implementation phase. WLCG Grid Deployment Board, CERN 13 May 2008

  4. The document and validation • 2 main parts: • A detailed description of a full solution implementation independent • Implementation plans per storage solution are also detailed with dates for each of the features. • A summary of what can be achieved by the end of the year per implementation • For the partial and full solutions a test suite will be ready for the validation of the implementations • Most probably also a draft plan for certification and deployment will be included in the document. WLCG Grid Deployment Board, CERN 13 May 2008

  5. The MoU Addendum • Spaces, files, copies and TURLs are defined • The behavior of the implementations for a set of operations has been clarified. • srmRm it is an operation on namespace only. • srmLs must return the arrayOfSpaceTokens. • srmPurgeFromSpace removes disk copies only. • srmBringOnline can be used to bring a file in a different space • srmPrepareToPut/PutDone does not allow to specify for how long the created copy stays on disk. This is system specific. • It is not possible to release copies created via a Put cycle or via an srmCopy operation. • At the moment srmCopy does not allow to pass tokens and destination copy lifetime. We will use a specific SRM structure to pass this info. Clients would need to be modified to check this structure. • srmReleaseFiles must be properly implemented to allow releasing of files without specifying the request ID. WLCG Grid Deployment Board, CERN 13 May 2008

  6. The MoU Addendum • Clients can now specify tokens for space selection on srmPrepareToGet, srmBringOnline, srmCopy • srmChangeSpaceForFiles is not mandatory • Space Tokens can be specified on Get • The concept of file primary copy is not used in WLCG • No tape transitions are allowed in WLCG • srmLs fileLocality parameter reflects the status of all copies. • If there is a nearline copy of a file in T1D0 and another online copy in T0D1, the status of the file is NEARLINE_AND_ONLINE • To optimize tape usage the structure TExtraInfo can be used to pass additional implementation specific info that are ignored by other implementations WLCG Grid Deployment Board, CERN 13 May 2008

  7. The MoU Addendum • Access Control Lists and a set of allowed operations are defined on spaces. Administrative interface. • Read/Write/Stage/Purge are mandatory operations • Release/Update/Query/Modify-ACLs are optional • More granularity with implementation specific features • Permissions on spaces are expressed in terms of DNs and/or VOMS FQANs. Optional FQAN wildcards. • ACLs can be positive or negative. fqan:dteam/Role=production:RSWQP:ALLOW fqan:dteam/Role=lcgamin:DURWSPQM:ALLOW fqan:dteam RSQ:ALLOW fqan:EVERYONE:DURWSPQM:DENY • NFSv4-type ACLs with either POSIX or NFSv4 matching algorithm • Definition of ACLs modification operations WLCG Grid Deployment Board, CERN 13 May 2008

  8. Questions for exps • Comments on pinning copies ? • Pinning on Put is implementation specific • Pinning will remain soft for some implementations • The space after a file removal operation will not be made available immediately • srmLs fileLocality returns the status of all copies • srmReleaseFiles with no requestID • Is this needed ? Please, provide valid use cases. Sign with the name of the experiment and person providing usecase. • Comments on protecting spaces • Is this enough ? • It will slow down operations ? • Wildcards on FQAN • Anything else ? WLCG Grid Deployment Board, CERN 13 May 2008

  9. Thank You WLCG Grid Deployment Board CERN, 14 May 2008

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