Grid Checkpointing · XtreemOS IP project is funded by the European Commission under contract...
Transcript of Grid Checkpointing · XtreemOS IP project is funded by the European Commission under contract...
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XtreemOS IP project is funded by the European Commission under contract IST-FP6-033576
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Grid CheckpointingJohn Mehnert-Spahn
Heinrich-Heine University Duesseldorf, Germany
XtreemOS Summer School, Günzburg, Germany, 2010
XtreemOS IP project is funded by the European Commission under contract IST-FP6-033576
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Checkpointing
XtreemGCP
Communication channel checkpointing with heterogeneous checkpointers
( Adaptive Checkpointing – incremental grid cp )
Overview
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Grid Jobs
Paris London Duesseldorf Barcelona
Job A running in a VOJob unit A1 Job unit A2 Job unit A3 Job unit A4
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Faults
Paris London Duesseldorf Barcelona
Job A running in a VOJob unit A1 Job unit A2 Job unit A3 Job unit A4
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Fault tolerance needed
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Fault tolerance
Replication
Forward error recovery
Backward error recovery
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XtreemOS IP project is funded by the European Commission under contract IST-FP6-033576
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Checkpointing & Restart
Checkpointing: The application state is saved periodically to stable storage.
Restart: The application gets reestablished from a recent checkpoint. Thus, no fall back to the initial state will occur.
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XtreemOS IP project is funded by the European Commission under contract IST-FP6-033576
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Checkpointing & Restart
Checkpointing: Saving periodically the state of the application in stable storage
Restart: In case of a fault we can restart from a checkpoint and do not fall back to the initial state
Challenges: Trade-off between costs during fault-free execution and costs at recovery
Size of the distributed state may be very large
Checkpointing images must be replicated
Heterogeneity of checkpointer packages
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Many Checkpointers exist
CoCheck
Condor
DCR
DMTCP & MTCPBLCR
LAM/MPI&BLCRzap
CLIP
libckpt
Dynamite
LinuxSSI
Linux-native
OpenVZ
tmPVM
VMWare player
Ckpt
CHPOX
CRAK
UCLiK
Epckpt
MCR
SCore
TICK
VMADump
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KMU
CP/R
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Workflow: Coordinated CP
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XtreemGCPcheckpointing service
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XtreemOS IP project is funded by the European Commission under contract IST-FP6-033576
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XtreemGCP
A grid service integrated within AEM implementingjob migration and job fault tolerance for grid jobs
Integrates existing checkpointer packages
Supports transparent and application-level checkpointing
Security
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Grid-Checkpointing Architecture
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Grid-Checkpointing Architecture
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Grid-Checkpointing Architecture
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Grid-Checkpointing Architecture
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Grid-Checkpointing Architecture
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Grid-Checkpointing Architecture
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Grid-Checkpointing Architecture
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Uniform Checkpointer Interface
Uniform access to different checkpointer packages implemented by a translib (shared library)
Translations• function signatures• job-to-Linux process group• grid user id-to-local user id• callback management• checkpoint image dependencies• checkpointer-to-checkpointer• application-checkpointer-compatibility
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To which extent must existing checkpointers be adapted to support various checkpointing protocols?
We need the following sequences Stop Checkpoint Resume_cp
Rebuild Resume_rst
Uniform Checkpointer Interface
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Checkpoint
Restart
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Currently, supported checkpointer packages
BLCR
OpenVZ
MTCP
LinuxSSI
(Linux native)
Uniform Checkpointer Interface
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Checkpoint files
Must be replicated
And accessible from each grid node
Stored in XtreemFS, providing: Stripping Automatic replication Location-transparent access Access control via XtreemOS user accounts
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Coordinated Checkpointing Workflow
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
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Coordinated Checkpointing Workflow
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
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Coordinated Checkpointing Workflow
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
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Coordinated Checkpointing Workflow
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
job metadatajobunit metadatacheckpointer images
sync/split/replicate
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Independent Checkpointing Workflow
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
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Independent Checkpointing Workflow
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
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Independent Checkpointing Workflow
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
job metadatajobunit metadatacheckpointer images
sync/split/replicate
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job-unit Checkpointer
Job Checkpointer
LinuxSSI cluster Linux
Independent Restart Workflow (during application runtime)
receive determinants (create dependency graph)
wrappers for send, recv, etc. (LD_PRELOAD)
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Job Checkpointer
Independent Restart Workflow
calculate recovery line from received determinants
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Translation Library
LinuxSSI Checkp.
Job-unit Checkpointer
Translation Library
BLCR
Job Checkpointer
LinuxSSI cluster Linux
Independent Restart Workflow
restart from CP1
rollback to CP2
Job-unit Checkpointer
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Measurements
Checkpoint Restart
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Callback Management
Implemented in generic part of translib
Called before and after a checkpoint and after restart
Common API for application callback registration
Useful for: Application-level checkpointing Application-level enhancements/optimizations System-level checkpointing of communication channels
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Workflow: Coordinated CP
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Channel checkpointing with heterogeneous checkpointers
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Consistent Checkpoints- in-transit messages -
orphan message
lost message:
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Soluition save in-transit messages
Marker-based approach
Challenges in the grid context
Node A Node B
Marker
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Marker-based approach
Challenges • incompatible checkpointers must cooperate• migration support• transparency (application, checkpointer, operating system)
Node ACheckpointer X
Node B
„This is my marker.“
Challenges in the grid context
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Marker-based approach
Challenges • incompatible checkpointers must cooperate• migration support• transparency (application, checkpointer, operating system)
Node ACheckpointer X
Node BCheckpointer Y
„This is my marker.“ „What's that? A normal paket with no specific meaning.“
Challenges in the grid context
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Architecture
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Gridkanalsicherung- Messungen -
Nachrichtenlänge und Sendefrequenz ohne Auswirkungen
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Workflow: Coordinated CP
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Adaptive checkpointing
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Incremental Checkpointing• write-bit• reflect dynamical memory layout changes• mprotect und jsdl
Adaptive Checkpointing- Incremental Checkpointing -
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Adaptive Checkpointing- Incremental Checkpointing -
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Adaptive Checkpointing- Incremental Checkpointing -
Common Checkpoint Incremental Checkpoint
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Adaptive Checkpointing- Incremental Checkpointing -
Common Restart Incremental Restart
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Summary
XtreemGCP offers migration and fault tolerance in grids by
providing checkpointing and restart
It is designed for heterogeneous setups integrating
existing checkpointer packages
Future work:
virtual machine support & adaptive checkpointing
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Acknowledgment
EC for funding XtreemOS
XtreemOS- GCP contributors: Heinrich-Heine Universität Düsseldorf
John Mehnert-Spahn, Eugen Feller INRIA, Rennes, France
Christine Morin, Thomas Ropars, Surbi Chitre, Stefania Costache
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