GARA: An Architecture for Advanced Reservations

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GARA An Architecture for Advanced Reservations

• Alain Roy
• Argonne National Laboratory
• (roy_at_mcs.anl.gov)

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Goals

• Provide end-to-end Quality of Service to
  applications. This requires
• Discovery and selection of resources
• Allocation of resources
• Advance reservation of resources

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Difficulties/Solutions

• Lack of support for advanced reservations
• We can use existing advanced reservation
  mechanisms if available or supply our own
• Heterogeneous resources
• We provide uniform interfaces
• Need to work with complex sets of resources
• We use co-reservation agents

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Solution GARA Globus Architecture for
Reservation and Allocation

• Three important contributions
• Advance reservations are first-class entities
• Uniform treatment of underlying resources
• CPU, network, disk, etc...
• Layered architecture enables generic
  co-reservation agents

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GARA BasicsReservations

• There is a generic reservation, which has
  several properties
• Start Time (now or future) and Duration
• Resource type/Underlying resource identifier
• Resource-specific (bandwidth, CPU)
• All reservations are treated uniformly
• Create/Modify (Given properties)
• gt Returns Reservation Handle
• Destroy
• Monitor (Callbacks or Polling)

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A picture of what happens(creating a reservation)
Create
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A picture of what happens(claiming a
reservation)
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Example Network reservation

• In advance, make a reservation
• RSL
• (reservation-typenetwork)
• (start-timenow1800) (duration3600)
• (endpoint-a128.135.11.4) (endpoint-b128.135.11.1
  )
• (bandwidth1000)
• Handle Opaque string H1
• At run-time, both ends do
• Bind(H1, portA, portB)

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The Resource Manager

• To track advanced reservations, we use a simple
  slot table
• We assume exclusive access to resource through
  the resource manager
• We arent tied to this particular resource manager

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Co-Reservation Agents

• When multiple resources are needed, an agent
• Discovers applicable resources via the MDS
• Reserves resources
• Informs user when resources are ready.
• The uniform interface enables these agents to be
  created easily.
• Given this ease, it is convenient to express
  different strategies such as
• Depth-first vs. best-first
• Coping with failures

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The Big Picture
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End-to-End Network Reservations

• Algorithm for a single network reservation
• Discover which gatekeepers/resource managers need
  to be contacted (MDS)
• Make reservation at each one.

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The GARA API

• globus_gara_reservation_create()
• Gatekeeper contact
• RSL reservation specification
• Reservation Handle or Error
• globus_gara_reservation_modify()
• Old Reservation Handle
• RSL reservation specification
• New Reservation Handle or Error

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The GARA API (continued)

• globus_gara_reservation_cancel()
• Reservation Handle
• Error
• globus_gara_reservation_status()
• Reservation Handle
• Status/Error
• globus_gara_reservation_callback_register()
• Reservation Handle
• Callback Function/User Parameter
• Error

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The End-to-End Agent API

• For making network reservations
• Deals with co-reservation along path.
• Very similar to GARA API
• Ex globus_gara_end2end_create()
• Handles MDS lookups.
• Handles making multiple reservations, but
  provides user with single reservation handle.
• Probably the API you want to use.

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Current Status

• A working prototype of GARA exists
• Differentiated Services-like QoS
• Real-Time CPU Scheduling (DSRT)
• DPSS Disk Access
• An early prototype of the end-to-end reservation
  agent exists.
• Validation and experiments are being done
  concurrently on a testbed.
• Work with bleeding-edge adopters is beginning to
  start.

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Future Work

• Deployment with Globus
• Supporting more resource types
• Job Schedulers
• Alternate Network QoS (RSVP)
• Disk (GRIO)
• Others (Memory, etc)
• Experimentation with real applications
• High-level agents to simplify usage.