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SRM 2.1 issues

SRM 2.1 issues. j.jensen@rl.ac.uk hepsysman Oxford 5 Dec 2005. Reminder – SRM. “Storage Resource Manager” Control protocol. What it does: Ask to make file ready for upload/download Basic metadata (size, checksum,…) Many components optional Web service (over GSI HTTP)

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SRM 2.1 issues

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  1. SRM 2.1 issues j.jensen@rl.ac.uk hepsysman Oxford 5 Dec 2005 Storage Middleware

  2. Reminder – SRM • “Storage Resource Manager” • Control protocol. What it does: • Ask to make file ready for upload/download • Basic metadata (size, checksum,…) • Many components optional • Web service (over GSI HTTP) • A Storage Element with an SRM interface is often called “an SRM” Storage Middleware

  3. Reminder – SRM • What it doesn’t: • Data transfer • Except it can do third party transfer • Access control & permissions • Some have tried to implement it Storage Middleware

  4. Reminder: baseline • “Give us SRM 2.1,” they said. • Pin/unpin • Space reservation • Volatile and permanent “space” (space?) • Directory stuff • VOMS & permissions • Abort, suspend/resume requests • getProtocols() Storage Middleware

  5. interoblems • SRM 2.1 is really SRM 2.1.1  • Two versions: 2.1.1 and 2.1.1-modified  • 2.1.1 has a more soapy array handling  • Most are now implementing 2.1.1-modified • DPM has switched, as of 1.4.1 • Publishing? • Both 1.1 and 2.1 are called “SRM” ? ? Storage Middleware

  6. interoblems • Much of the API is optional • Some things are genuinely optional • Clients don’t use full API so why implement all • “Extra” features • Access control • Interop is more than using same WSDL • API is quite complex (much more than 1.1) • Semantics, my dear, semantics Storage Middleware

  7. interoblems SRM2 SRM2 put cycle srmCopy The Chocolate and Vanilla and Strawberry problem Client srmCopy SRM2 SRM2 Storage Middleware

  8. interoblems • Not all sites will upgrade at the same time • Some sites will continue to publish 1.1 • Even DPM has two different daemons • So they compete for 8443  • Must be able to upload via one interface and download via the other  Storage Middleware

  9. What should lost Aeneas do? Colourful solution Each flavour can talk to any other flavour Storage Middleware

  10. What should lost Aeneas do? Common client can talk to all flavours Storage Middleware

  11. Use get/put for file transfer for now… GridFTP 3rd party xfer SRM2 SRM2 srmGet srmPut Client Storage Middleware

  12. Then Wait • SRMs will interoperate • SRMs are converging • Needs testing though • They will use 2.1.1-modified • They will be able to use srmCopy between SRMs  Pessimist Optimist Storage Middleware

  13. Implementations • dCache • Provides 1.1 since forever • 2.1 (FNAL) “expected mid January” • We won’t meet storage goals if 2.1 is delayed • Upgrade from 1.5.{2,3} via 1.6.6 Storage Middleware

  14. Implementations • DPM • Provides 1.1 and 2.1 since, uhh, quite a while • Now uses 2.1.1-modified  • Can publish both interfaces at same time  • But not on the same web service port  Storage Middleware

  15. Other Implementations • Not supported for Tier 2 deployment • CASTOR2 SRM • Developed at RAL • Deployed at CERN (other CASTOR sites later) • StoRM • Developed at INFN • Not tested in UK yet • Thin layer, depends on underlying filesystem Storage Middleware

  16. Testing • 2.1 clients developed with DPM • RAL developing more elaborate testing framework • GOC deploying SE monitoring • Easily adapted to 2.1s Storage Middleware

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