DB2 and Advanced Copy Services: All You Need to Know

Transcription

1 DB2 and Advanced Copy Services: All You Need to Know aul endle ndependent Consultant Tuesday, March 11, 2014 Session Number: 15352

2 Agenda What is/are Advanced Copy Services Deep dive into FlashCopy Shallow dip into RC/XRC Using FlashCopy in z/os Consistency Groups Using DB2 with FlashCopy Considerations for using DB2, FlashCopy, and RC/XRC Conclusions 2

3 ntroduction to Advanced Copy Services Storage array facilities that replicate data Locally (FlashCopy) Volume to Volume Dataset to dataset Long distance (RC, XRC) Synchronously and asynchronously Volume to volume 3

4 Array-based Local Replication TSO CKDSF ADRDSSU ANTRQST F7 Source Target 4

5 Array-based Copy Advantages No host CU or /O to perform the data movement Extremely fast copies Both dataset and volume replication Allows incremental copies Can allow space efficient copies (FlashCopy SE) Time-to-use very fast (before copy completion) 5

6 FlashCopy rimitives ESTABLSH Creates a relationship between a source and target volume/dataset and in most cases copies the data from source to target WTHDRAW Terminates a FlashCopy relationship between a source and target What s missing? RESTORE!!!!!!! ESTABLSH with FAST REVERSE RESTORE. 6

7 FlashCopy Considerations Establish is three phases Create the relationship (very fast) Copy the tracks (optional: NOCOY) Withdraw the relationship (optional and very fast) Three FASTRELCATON modes under DFDSS REFERRED (default) REQURED NONE Copy on first write (COFW) overhead Read indirection overhead 7

8 FlashCopy Relationships (Temporary) Source Establish Target rotection map ndirection map

9 FlashCopy Relationship (ersistent) Source Establish Target rotection map ndirection map Space Efficient NOCOY ncremental

10 How Does ncremental Help? Source Establish Target rotection map ndirection map

11 ncremental FlashCopy Considerations Reduced work for the storage controller Faster completion of background copy Reduced COFW impact Reduced indirected reads Only one FlashCopy session can be incremental Others are withdrawn on completion 11

12 ncremental Limitation (Full Volume) Source Target Target Target Target Target Target Target Target Target Target Target Target 12

13 Cascading FlashCopy Source Target Target Source Source Target 13

14 Space Efficient FlashCopy SE DEVCE Source 0 Establish Repository

15 Space Efficient FlashCopy Restore T1 Source 0 T2 S Repository

16 Space Efficient FlashCopy lanning On DS8xxx requires a separate license from basic FC Requires dedicated FCSE devices in the DS8xxx config Careful planning is required Has performance impact Change rate during life of FC session <5% Repository can fill up: EA499E warnings/errors Repository cannot be dynamically expanded Need to withdraw the relationship Delete, reconfigure and redefine the repository

17 17 FlashCopy Consistency Groups

18 DB2 Status when replicating For the purposes of the replicating operation there are only three states that a DB2 database can be in when you are going to copy it: Shut down n log suspend mode Running normally

19 Dependent-Write Consistency DB2 never makes a change to the database without logging the change first (ARES principle) Transaction Changes Transaction state Action on Restart n buffer pool Uncommitted Discarded On disk Uncommitted Undo process n buffer pool Committed Redo process On disk Committed No action necessary

20 FlashCopy Consistency S T S T S T S T S T S T LCU

21 FlashCopy Outside of DB2 Needs: Consistency groups or Log suspend Can replicate beyond the DB2 domain using Con Groups MS, Other DB2, MQ, VSAM, CCS roduces a restartable image 21

22 DB2 and FlashCopy A brief history

23 DB2 V8 and FlashCopy System oint-in-time Recovery (SYSTR) Backup System utility (DSNUTLB) mplemented for very large applications (e.g. SA) Only stage one (disk copy) DFSMS 1.5 or later oor integration with DB2/HSM/SMS Difficult to trouble-shoot DB2 domain only FC support for CHECK NDEX SHRLEVEL CHANGE 23

24 SYSTR Timeline DSNUTLB Backup System DB2 suspends checkpoints, DDL, changes to CF catalogs, 32KB writes Update BSDS with RBL Update DSNDB01 with oldest log record (HGLBRBA) FlashCopy database pool volumes (any order) FlashCopy log pool volumes (any order) Update BSDS with SLB information Release restrictions Withdraw FlashCopy relationship 24

25 DB2 V9 and FlashCopy SYSTR Dataset restore from SLB Still using SMS/HSM Capability to dump target volumes DUM/DUMONLY Some CF catalog issues for datasets being moved FC support for CHECK NDEX SHRLEVEL CHANGE FC support for CHECK LOB SHRLEVEL CHANGE DB2 domain only 25

26 DB2 V10 and FlashCopy SYSTR CF catalog issues resolved (mostly) ncremental Flash enabled BACKU SYSTEM ESTABLSH FCNCREMENTAL Still using HSM/SMS DB2 domain only 26

27 DB2 Full Volume Cloning Source Devices Target Devices BSDS Recovery Structures CF User Catalog Recovery Structures Archive Logs BSDS Active Logs 4001 Archive Logs CF User Catalog 1005 DB2 Catalog 4004 CF User Catalog 4005 Data Structures Data Structures 1006 Table Spaces 1007 DB2 Directory 4006 Table Spaces 4007 Storage Controller CF User Catalog Active Logs DB2 Catalog DB2 Directory

28 DB2 and Other FlashCopy Functions ZARM CHECK_FASTRELCATON= (REFERRED/REQURED) Some utilities can use FlashCopy CHECK DATA CHECK NDEX CHECK LOB REORG TS REBULD NDEX REORG NDEX COY LOAD FCC in DB2 V10 With consistency! 28

29 FlashCopy, DB2, and Remote Replication

30 Array-based Remote Replication Synchronous (Metro Mirror aka RC) W W RC Source RC Target 30

31 Considerations for Synchronous Replication Write performance Log writes VSAM striping can help mitigate some latency Synchronous buffer pool writes age steal writes ncreased DSC time Database consistency Distance impact on writes Every 200km miles adds 2ms additional latency (round trip)

32 SDM Array-based Remote Replication Asynchronous (z/os Global Mirror aka XRC) W RC Source W Target 32

33 Considerations for Asynchronous Replication XRC Host write performance largely unaffected z/os timestamps the writes Writes are accumulated in a side file System data mover on the target side reads the side file Some data loss is expected

34 Array-based Remote Replication Synchronous (RC) rimary1 DULEX Secondary1 F C rimary2 DULEX ENDNG Secondary2 34

35 Duplex ending Status Generally not acceptable in RC installations Secondary site may not be recoverable HyperSwap event will fail 35

36 Solutions to Duplex ending ssue SYSTR Set up COY OOLs outside of RC DB2 utilities oint temporary files at non-rc SMS storage group ZARM UTL_TEM_STORCLAS 36

37 reserve Mirror and RC AKA Remote air FlashCopy rimary1 DULEX Secondary1 F C F C rimary2 DULEX Secondary2 37

38 reserve Mirror Considerations Requires specific microcode levels and AARs FlashCopy Source and Targets must be RC rimary volumes HyperSwap will work when reserve Mirror is used Copy work performed by FlashCopy does not have to be transmitted across the network 38

39 DSNZARM FLASHCOY_RC Values NONE results in DULEX ENDNG REFERRED means DULEX ENDNG is allowed REQURED means DULEX ENDNG is not allowed (GDS) Blank no preserve mirror command sent to DFSMSdss Applies to DB2 Utilities CHECK DATA/NDEX/LOB REORG TABLESACE/NDEX REBULD NDEX LOAD COY/RECOVER 39

40 DB2 Utilities using DFSMShsm and reserve Mirror No ZARM settings oddly reserve Mirror attribute set at the Copy ool level in SMS FRBACKU (NO N R) FRRECOV (NO N R) 40

41 FlashCopy, DB2, and XRC FlashCopy to a XRC source is not allowed Consider how z/os timestamps the writes BACKU SYSTEM Keep copy pools separated from XRC Restore System cannot use FlashCopy Or disable mirroring Object recovery slow replication DB2 utilities oint temporary files at non-xrc SMS storage group ZARM UTL_TEM_STORCLAS 41

42 Drivers for Selecting the ACS Solution Restartable or recoverable Federated with other applications/platforms z/os DB2 LUW MQ Space efficient copies DB2 availability Volume or dataset Object restore requirements ntegration with DB2 recovery Considerations for remote replication 42

43 Conclusions FlashCopy replication can enhance: System backup and restore Object backup and restore Care must be taken to deploy the correct options for a given situation More care is necessary when using remote replication Collaborate closely with system programmers and storage administrators for success 43

44 DB2 and Advanced Copy Services: All You Need to Know aul endle ndependent Consultant Tuesday, March 11, 2014 Session Number: 15352