CCRC08SSWGStorageBusyMeeting090211 < LCG

LCG Web>WLCGCommonComputingReadinessChallenges>CCRC08SSWGStorageBusyMeeting090211 (2009-02-12, AndreaSciaba) (raw view)

---++ Pre-meeting on "busy" storage services (11/02/2009)

---+++ Participants
J.P. Baud, F. Donno, A. Frohner, E. Lanciotti, G. Lo Presti, R. Mollon, A. Sciab&agrave;, D. Smith, P. Tedesco

---+++ Conclusions
Suggesting that the client specifies _desiredTotalRequestTime_ and the server should do its best to abort a request, if the time is reached and the client did not abort it explicitly (i.e. the client has crashed). Returning _remainingRequestTime_ is desirable but less important.

Suggested a back-off algorithm on both synchronous and asynchronous methods: *if an SRM_INTERNAL_ERROR is received, the client shall use an exponential retry period on the same operation*.

Suggested an asynchronous polling method:

   1. send an _srmPrepareToGet/Put_
   2. in a loop with an exponential retry period until something changes: _srmGetRequestSummary_ (lighter on the SRM)
   3. use _srmGetStatus_ to get the details of the change.

On the metascheduling level: it is very hard to give a meaningful estimate on how "busy" is the SE, so we give up on that for now.

-- Main.AndreaSciaba - 12 Feb 2009

Topic revision: r1 - 2009-02-12 - AndreaSciaba

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