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Evaluation of Objectivity Databases on the Sony HSM Software and Tape Robotics

Evaluation of Objectivity Databases on the Sony HSM Software and Tape Robotics. Michael Athanas Cornell Univ. * and Nobu Katayama, Atsushi Manabe KEK. * on leave to Cereon Genomics. Motivation.

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Evaluation of Objectivity Databases on the Sony HSM Software and Tape Robotics

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  1. Evaluation of Objectivity Databases on the Sony HSM Software and Tape Robotics Michael Athanas Cornell Univ.* and Nobu Katayama, Atsushi Manabe KEK * on leave to Cereon Genomics

  2. Motivation • In upcoming HEP experiment, managing a huge volume of complex data is necessary. For handling such a data, Objectivity/DB is becoming a popular choice in HEP. • Better understanding of how the Objectivity/DB works with a rather conventional Hierarchical Storage Management system (HSM). Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  3. HSM pros and cons • Popular software on many venders and affordable. • Unit of transfer between disk and tape is file • access time overhead • space inefficiency • User cannot assign any tapes to store the file. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  4. Prototyping Test • Schema: Based on Cornell Nile Proj*/objyDB. * presented in CHEP97 • Data Base software: Objectivity/DB 4.0.10 • Hardware: A part of the KEKB computer system. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  5. Test Bed System (1) Tape Lib. • Server:SUN UE 6000 (US1 166 MHz x4CPU) • Tape Library: Sony PetaSite* : 30TBSony DTF (8MB/s) x 8 • Disk: MSS RAID 80GB • HSM soft: Sony PetaServe* (OSM ver.2.1 base) SCSI2/W WS SCSI2/W RAID * http://www.sony.com/professional Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  6. Test Bed System(2) • HSM disk Layer: 10GBytes • HSM tape Layer: 100GBytes • Tape Media Capacity: 10GB/tape • HSM Water Mark:(adjustable param.) High (force data move to tape) =8GB Low (move until this size) =4GB Shadow =1GB Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  7. Test Bed System(3) • Disk • Max. read/write rate: 8/8 MB/s • Tape • Max. read/write rate: 12MB/s • media loading time: 30~60 sec (with positioning & mounting) • Network • DB Clients & Server are on the same machine • Disk and Tape are attached locally Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  8. Class association DataSetCollection DataSet(Hadron) ……….... DataSet(Taus) x 100 RunCollection(1) ……….. RunCollection(100) x10 Run(1) ……….. Run(9) x1000 Event(1) ………….. Event(1000) ……….. EventRecord EventRecord Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  9. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  10. Each DB is a UNIX file and Unit of HSM migration

  11. Data Size • Event Inf. ~50B • Event Record 4k~16kB • Run Inf. ~50B • RunCollection DB size = ~ 120MB • Total DataSet size = ~12GB • Tape Media Size = 10GB (small type media ) Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  12. Population (object creation) • PageSize = 64kB • DataSet = 12GB population. • Single process / Multi process concurrent population Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  13. Population flow diagram Define DB file disk 10GB Begin Run Obj write Run Loop 50B Commit RunCollection Loop Event header write ~12kB >Over HighWM Event Record write & close 50B End Run Obj write Commit Tape 100GB Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  14. Population test result • Average write Rate: 1.2MB/sec • 1 DataSet (12GB) creation • Tape migration was negligible. • NO HSM overhead was seen. • Population in parallel (multi process) • Scalability: saturation was seen.(memory shortage ?) Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  15. Population speed Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  16. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  17. Data base access (1) • Access pattern can make big difference in its performance. • Data reloading time (Tape->Disk) affects much. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  18. Data base access (2) • Deep Scan • Load all data into memory • Light Scan • Just Event header data is scan. • Index Scan • 1/200 data access by event number Index search (ooEqualLookup). • At first all data are moved to Tape (migrate) then start access. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  19. Deep Scan • 6GB full scan (500 Runs) • On HSM • 3.4MB/sec 337 obj/sec 1482s • On normal disk (reference) • 7.3MB/sec 725 obj/sec 690s • Tape Reloading Time (reference) • 50x120MB file 1100s Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  20. Light Scan • 250MB scan in 6GB (500 Runs) • On HSM • 28kB/sec 568 obj/sec 880s = 5.7MB/sec seq. access equiv. • On normal disk (reference) • 830kB/sec 16k obj/sec 30s = 166MB/sec seq. access equiv. • Tape Reloading Time (reference) • 50x120MB file 5.5MB/s 1100s Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  21. Index Scan • 30MB (0.5%)scan in 6GB (500 Runs) • On HSM • 27kB/sec 2.7 obj/sec 950s = 5.3MB/sec seq. access equiv. • On normal disk (reference) • 116kB/sec 12 obj/sec 210s = 23MB/sec seq. access equiv. • Tape Reloading Time (reference) • 100x120MB file 6MB/s 1002s Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  22. Seq. access equiv. speed • Required speed in using conventional sequential tape scan to fetch the data in the time. • Speed = Total Scaned object size /elapsed time • Seq. acc. equiv. speed = Total data size /elapsed time Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  23. Event Search EventAtr= XXX RUN(I) Event Record Index table RUN(I+1) objyDB/HSM Conventional Tape access Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  24. Index scan access speed on HSM on pure disk Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  25. Conflicting tape access • Index Search with multi processes • 1 process/HSM31kB/sec 2.7 obj/sec 950s = 6.3MB/sec seq. access Equiv. • 2 process/HSM with access conflict7kB/sec 0.6 obj/sec 3900s = 1.5MB/sec seq. access Equiv. • 2 process/Disk (reference)1.7MB/sec 13 obj/sec 200s= 30MB/sec seq.access Equv. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  26. Typical conflict situationSimultaneous access to single tape Process 1 Back & Forth Process 2 Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  27. Summary (1) • ObjectivityDB + PetaServ (HSM) generally works well. It could be a cost effective solution. • HSM overhead in DB write (populate) was negligible in our program. More efficiency was achieved by concurrent population with multiple processes. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  28. Summary(2) • The performance of accessing data directly from the HSM under three access pattern was measured. • The access tests showed that objyDB/HSM could get comparable speed with conventional sequential tape access in addition to the OODB merits. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

  29. Summary(3) • Conflictive access to single tape among processes much degrades DB access speed. To avoid such a situation, access scheduling is one of a solution. • Strategy: • Access DB file in the order of tape file position. • Avoid concurrent accesses to DB files in single tape. Evaluattion of Objy/DB on Sony HSM. CHEP 98 CHICAGO

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