© 2010 Open Grid Forum Choices in Reservation operation 1PC/2PC, timing Tomohiro Kudoh, AIST

© 2010 Open Grid Forum Reservation options 1PC/2PC 2PC has held state, and must be committed before provisioning Start time parameter Advance / immediate Trigger of provisioning Explicit: signaling message from the root requester Automatic: Each leaf provider NSA provision at the specified start time based on its own timer 2

© 2010 Open Grid Forum Advance reservation (1PC) 3 CoordinatorCohort aCohort b reserve granted I R CoordinatorCohort aCohort b reserve not-granted granted roll-back (cancel) all casenone case Reservation without Provisioning can be roll- back. If one of providers (cohorts) can not grant request, coordinator can ask other cohorts to roll- back before provisioning. I R I R I R I R I R I R I R I R I: Initial R: Reserved

© 2010 Open Grid Forum Immediate reservation (1PC) 4 CoordinatorCohort aCohort b request granted I P CoordinatorCohort aCohort b request not-granted granted roll-back all casepartial case Resources are provisioned when granted The coordinator cannot ask to cancel before provisioning I P I P I P I P I P I P I P I P I: Initial P: Provisioned Roll-back is not possible (or painful) since the resource is already provisioned.

© 2010 Open Grid Forum What is two phase commit protocol? An atomic commitment protocol Used in transaction systems such as data bases Guarantees all or none of multiple participants (cohorts) are done (committed). 5 CoordinatorCohort aCohort b commit request commit request held commit I AH C I AH C I AH C I AH C I AH C I AH C CoordinatorCohort aCohort b commit request commit request abort held abort I AH C I AH C I AH C I AH C I AH C I AH C all casenone case I: Initial H: Held A: Aborted C: Committed

© 2010 Open Grid Forum When is 2PC required? 2PC is a protocol to support roll-back A held transaction can be rolled-back When a transaction is inherently rolled-back- able, atomic commitment protocol (2PC) is not mandatory Usually, reservation can be rolled-back, provisioning may not. Use 2PC when it is required (strongly preferable). 6

© 2010 Open Grid Forum Immediate reservation with 2PC Committed = Provisioned Roll-back is request before actual provisioning of resources 7 CoordinatorCohort aCohort b commit request commit request held commit I AH C I AH C I AH C I AH C I AH C I AH C CoordinatorCohort aCohort b commit request commit request not-granted held abort I AH C I AH C I AH C I AH C I AH C I AH C all casenone case I: Initial H: Held A: Aborted C: Committed

© 2010 Open Grid Forum But If you do not make a reservation advance enough, the reservation becomes immediate, instead of advance. It is not clear how much time is enough. So it is not reasonable to distinguish immediate and advance, and use different protocols. 8

© 2010 Open Grid Forum Simplified 2PC The cohort which is requested lastly does not have to support 2PC 9 CoordinatorCohort aCohort b commit request held commit I AH C I AH C I AH C request granted I P I P CoordinatorCohort aCohort b commit request held abort I AH C I AH C I AH C request not-granted I P I P

© 2010 Open Grid Forum Chain does not require 2PC between NSAs Chain model with 2PC 10 NSA NRM NSA NRM NSA NRM 2PC But can be simplified to use 2PC for internal-only No 2PC is required between NSAs. NSA NRM NSA NRM NSA NRM 2PC 1PC 2PC 1PC 2PC 1PC

© 2010 Open Grid Forum Timing issues we should aware The following timing issues exist, and must be considered Reservation time: Time (duration) required to process request, schedule and make resources ready for provision Set up time: Time (duration) between a trigger to provision (signaling message or timer) and the time when service for user become available Tear down time: Time (duration) between a trigger to cancel a provision (signaling message or timer) and the time service disappears Messaging time: Time (duration) required to deliver a message 11

© 2010 Open Grid Forum Provisioning timings(1) reservation start time The time a provider NSA starts action to provision a connection (by timer or signaling) No preceding processing before this time is required. reservation end time After this time, provision sequence of another reservation can be started service start/end time The time the user can start/should finish to use the connection 12

© 2010 Open Grid Forum Provisioning timings(2) ERSTEarliestReservationStart time reservation must not start before this time to keep ESST (?) LRSTLatestReservationStart time reservation must be started by this time to meet the service definition ERETEarliestReservationEnd time No meaning? LRETLatestReservationEnd time reservation must be ended by this time to allow next reservations provisioning ESSTEarliestServiceStart time service must not start before this time for security reasons. LSSTLatestServiceStart time User requires service by this time ESETEarliestServiceEnd time User requires service until this time LSETLatestServiceEnd time service must not remain after this time for security reasons 13

© 2010 Open Grid Forum 14 LRST LRET ESST LSST LSET ESET LRST ESST LSST

© 2010 Open Grid Forum Parameters of immediate reservation There was a discussion on whether to use (start time, end time) or (stat time, duration) for requesting parameters, and we decided to use (start time, end time) for NSI protocol They are the same for exact start time operation, duration = end time – start time But they are different for immediate reservation: (immediate, end time), (immediate, duration) If the end time is specified, duration of provisioning is not known, and vice versa. 15