tevfik kosar computer sciences department university of wisconsin-madison kosart@cs.wisc.edu ...

Tevfik KosarComputer Sciences DepartmentUniversity of Wisconsin-Madison

kosart@cs.wisc.eduhttp://www.cs.wisc.edu/condor

Managing and Scheduling Data Placement (DaP)

Requests

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Outline

› Motivation

› DaP Scheduler

› Case Study: DAGMan

› Conclusions

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Demand for Storage

› Applications require access to larger and larger amounts of data Database systems Multimedia applications Scientific applications

• Eg. High Energy Physics & Computational Genomics

• Currently terabytes soon petabytes of data

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Is Remote access good enough?

› Huge amounts of data (mostly in tapes)

› Large number of users› Distance / Low Bandwidth › Different platforms› Scalability and efficiency concerns=> A middleware is required

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Two approaches

› Move job/application to the data Less common Insufficient computational power on

storage site Not efficient Does not scale

› Move data to the job/application

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Move data to the Job

Huge tape library (terabytes)

Compute cluster

LAN

Local Storage Area (eg. Local Disk, NeST Server..)

WAN

Remote Staging Area

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Main Issues

› 1. Insufficient local storage area

› 2. CPU should not wait much for I/O

› 3. Crash Recovery

› 4. Different Platforms & Protocols

› 5. Make it simple

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Data Placement Scheduler (DaPS)

› Intelligently Manages and Schedules Data Placement (DaP) activities/jobs

› What Condor is for computational jobs, DaPS means the same for DaP jobs

› Just submit a bunch of DaP jobs and then relax..

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DaPS Architecture

DAPS Server

AcceptExec.

Sched.

DaPS Client

DaPS Client

Req.

Req.

GridFTP Server NeST Server

SRB Server

Local Disk

GridFTP Server

SRM Server Req.

Buffer

Req.

LocalRemote

Queue

Thirdparty transfer

Get

Put

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DaPS Client Interface

› Command line: dap_submit <submit file>

› API: dapclient_lib.a dapclient_interface.h

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DaP jobs

› Defined as ClassAds

› Currently four types: Reserve Release Transfer Stage

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DaP Job ClassAds[ Type = Reserve; Server = nest://turkey.cs.wisc.edu; Size = 100MB; reservation_no = 1; ……][ Type = Transfer; Src_url = srb://ghidorac.sdsc.edu/kosart.condor/x.dat; Dst_url = nest://turkey.cs.wisc.edu/kosart/x.dat; reservation_no = 1; ...... ]

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Supported Protocols

› Currently supported: FTP GridFTP NeST (chirp) SRB (Storage Resource Broker)

› Very soon: SRM (Storage Resource Manager) GDMP (Grid Data Management Pilot)

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Case Study: DAGMan.dagFile

CondorJobQueue

A

DAGManDAGMan

C

D

A

B

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Current DAG structure

› All jobs are assumed to be computational jobs

Job A

Job B Job C

Job D

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Current DAG structure

› If data transfer to/from remote sites is required, this is performed via pre- and post-scripts attached to each job.

Job A

PRE

Job BPOST

Job C

Job D

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New DAG structure

Add DaP jobs to the DAG structurePRE

Job BPOST

Transfer in

Reserve In & out

Job B

Transfer out

Releasein

Release out

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New DAGMan Architecture

.dagFile

CondorJobQueue

A

DAGManDAGMan

B

D

A

C DaPSJob

Queue

X

Y

X

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Conclusion

› More intelligent management of remote data transfer & staging increase local storage utilization maximize CPU throughput

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Future Work

› Enhanced interaction with DAGMan

› Data Level Management instead of File Level Management

› Possible integration with Kangaroo to keep the network pipeline full

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Thank You for Listening &

Questions

› For more information Drop by my office anytime

• Room: 3361, Computer Science & Stats. Bldg.

Email to:• condor-admin@cs.wisc.edu