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IBM Software Group
© 2008 IBM Corporation
IMS Application Dependent & Mirroring Overview Disaster Recovery Solutions
Glenn GallerIBM SW IT Specialist, ATSAnn Arbor, Michigangallerg@us.ibm.com
2
The following are trademarks of the International Business Machines Corporation in the United States and/or other countries.
The following are trademarks or registered trademarks of other companies.
* Registered trademarks of IBM Corporation
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Notes:
Performance is in Internal Throughput Rate (ITR) ratio based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput that any user will experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve throughput improvements equivalent to the performance ratios stated here.
IBM hardware products are manufactured from new parts, or new and serviceable used parts. Regardless, our warranty terms apply.
All customer examples cited or described in this presentation are presented as illustrations of the manner in which some customers have used IBM products and the results they may have achieved. Actual environmental costs and performance characteristics will vary depending on individual customer configurations and conditions.
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AIX*CICS*DB2*e-business logo*Enterprise Storage Server*ESCON*FICONFlashCopy*
GDPS*HyperSwapIBM*IBM eServer*IBM logo*NetView*OS/390*Parallel Sysplex*
S/390*Sysplex Timer*Tivoli*TotalStorage*z/OS*z/VM*zSeries*
Trademarks
3
Acknowledgments
• Peter Armstrong (BMC)• Book: “DBRC in Practice”
• http://www.dbazine.com/ofinterest/oi-articles/armstrong6
• Technical Support • Rich Lewis (ATS)• Helene Lyon (IBM France)
• DM Tools• Mitch Dooley and Lynne Bisceglia (IMS Recovery Expert)• Bob Magid (DM Tools Architect)
4
Agenda
• Two Disaster Recovery Strategies for IMS• IMS Application Dependent DR• Storage Management Mirroring
• IMS Application Dependent DR• Managing image copies, Recons, and Logs at a Remote Site• IBM DM Tools can assist with this DR strategy
• Storage Management Mirroring• Production data is mirrored to Remote Site• Creating Consistency is the Key• Mirroring can be Asynchronous or Synchronous• GDPS can be used to automate DR strategy
5
Concepts
• Disaster Recovery• Process of recovering a Production environment • Restore to point where business can be conducted
• Recovery Time Objective (RTO)• Time allowed to recover the applications • All critical operations are up and running again
• Recovery Point Objective (RPO)• Amount of data lost in the disaster• Last point-in-time when all data was current
6
IMS Application Dependent Disaster Recovery
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Production Site
Remote
Site
Logger
RECON
WADS
OLDS
RDS
IMS ControlRegion
DBRC
DLI/SAS Image Copies
RLDS
Change Accumulation
SLDS
BACKUP RECON
8
Remote Site
Logger
IMS ControlRegion
DBRC
DLI/SAS
RECON
Production
SiteRLDS
Image Copies
Change Accumulation
SLDS
BACKUP RECON
RDS
WADS
OLDS
9
3 Application Dependent DR Strategies
• #1: Recover the Databases to an Earlier Image Copy• Image Copies and Recon are shipped to remote site• Production activity is quiesced for image copy
• Procedure may include IMS, DB2 and CICS• Data since last image copy is lost• RTO is low since recovery time is short• RPO is high since the log updates are lost
Image Copies
10
3 Application Dependent DR Strategies
• #2: Recover the Databases to the Last Good Log Data Set• Image Copies, Recon, Logs are shipped to remote site• Forward and Backward recovery is performed with the logs• RTO is higher as recoveries are required• RPO is lower as log updates are applied to image copy
SLDS
RLDS
Change Accumulation
Image Copies
+
11
3 Application Dependent DR Strategies
• #3: Recover the Databases to the IMS Recovery Expert RP• Image Copies, Recon, Logs are shipped to remote site• Forward recovery is performed to the RP with the logs• RTO is higher as recoveries are required• RPO is lower as log updates are applied to image copy• IBM Tools provide additional capability
SLDS
RLDS
Change Accumulation
Image Copies
+ + RP
12
Recover DBs to Earlier Image Copy
13
Recover DBs to Earlier Image Copy
• Primary: Step 1: • Quiesce the IMS environment• Take Batch (Clean) Image Copies periodically• Ship Image Copies + Recon to Remote Site
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Recover DBs to Earlier Image Copy
• Remote: Step 2: Clean Backup Recon• Active Subsystems
• If Recon shows active SUBSYSTEMs• Use LIST.SUBSYS to show active subsystems• Issue DBRC Commands:
• CHANGE.SUBSYS SSID(ssidname) ABNORMAL• CHANGE.SUBSYS SSID(ssidname) STARTRCV• CHANGE.SUBSYS SSID(ssidname) ENDRECOV• DELETE.SUBSYS SSID(ssidname)
• Secondary Image Copies• If Image Copy at Remote site is a Secondary Image Copy
• Flag the Primary Image Copy in the Recon as Invalid• Fastpath DEDBs
• Flag DEDBs AREAs as Recovery Needed to enable recoveries
15
Recover DBs to Earlier Image Copy
• Remote: Step 3: Recover DBs to Clean IC• Use Cleaned Up Recon to for GENJCL.RECOV JCL • Recover database data sets:
• Standard IMS Recovery Utility (DFSURDB0)• Or, IMS Database Recovery Facility (DRF)
• HPIC Incremental Image Copies• Must be recovered with IMS Database Recovery Facility (DRF)
• HPIC COPY Image Copies• Exact copy of database, no recovery is needed• Ensure Database Data Set name matches
Image Copies Database Recovery
Utility or Tools
16
Recover DBs to Earlier Image Copy
• Remote: Step 4: Cold Start IMS Systems• Databases are consistent with earlier Image Copy
17
Recover DBs to Last Good Log
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Recover DBs to Last Good Log
• Primary: Step 1: • Take Batch (Clean) or CIC (Fuzzy) Image Copies• Optionally take Change Accumulations periodically• Ship ICs + Recon + SLDS/RLDS + CAs to Remote Site
19
Recover DBs to Last Good Log
• Remote: Step 2A: Clean Backup Recon • To use DBRC Recon for Recovery
•No Databases can be Allocated on an OPEN log
• Close and Archive OLDS in Recon data •When OLDS are not at the Remote Site•All PRILOG, PRISLD, PRIOLD need non-zero Stop Times
• Two Methods:1.Add dummy SLDS log entry and Start Archive2.Close & flag INUSE OLDS as Archive Needed & Archive
20
Recover DBs to Last Good Log
• Remote: Step 2B: Clean the Backup Recon • Active Subsystems
• If Recon shows active SUBSYSTEMs• Use LIST.SUBSYS to show active subsystems• Issue DBRC Commands:
• CHANGE.SUBSYS ABNORMAL• CHANGE.SUBSYS STARTRCV• CHANGE.SUBSYS ENDRECOV• DELETE.SUBSYS
• Secondary Image Copies• If Image Copy at Remote site is a Secondary Image Copy
• Flag the Primary Image Copy in the Recon as Invalid• Fastpath DEDBs
• Flag DEDBs AREAs as Recovery Needed to enable recoveries
21
Recover DBs to Last Good Log
• Remote: Step 2C: Clean the Backup Recon• If copies of CA data sets are at remote site
• Recon will show CA data sets from Production site• Use CHANGE.CA to point to correct copy of CA
• If CA data sets are unavailable and exist in Recon• Flag the Recon to show CA is INVALID
• DBRC will use the logs instead of the CAs
22
Recover DBs to Last Good Log
• Remote: Step 3: Recover DBs from ICs, Logs, CA• Use Clean Up Recon to GENJCL.RECOV JCL• Recover DBs from ICs + CAs + SLDS/RLDS
• Standard IMS Recovery Utility (DFSURDB0)• Or, IMS Database Recovery Facility (DRF)
• HPIC Incremental ICs• Use IMS Database Recovery Facility (DRF)
+Change Accumulation
RLDS
SLDS
Image Copies
RECON
+
23
Recover Database to Last Good Log
• Remote: Step 4: Batch Backout• Following Full Database Recovery
• Backout Inflight UOWs• Cold Start or ERE COLDSYS or ERE COLDBASE
• Following Timestamp (RP) or Point-In-Time Recovery• No Inflight UOWs to backout• Cold Start or ERE
24
Recover Databases to Last Good Log
• Remote: Step 5: Cold Start or /ERE from SLDS
• If /ERE From SLDS
• Ensure SUBSYS records have been cleaned up• Online IMS SUBSYS record should not be deleted
• IMS dynamically allocates SLDS• OLDS were archived for GENJCL.RECOV
25
Recover DBs to IMS Recovery Expert RP
26
Recover DBs to IMS Recovey Expert RP
• Primary: Step 1: Create Backup Datasets• Take Batch (Clean) or CIC (Fuzzy) Image Copies• Optionally take Change Accumulations periodically• Create IMS Recovery Expert RPs periodically• Create and Clean Backup Recon• Ship ICs + Clean Backup Recon + SLDS/RLDS + CAs
27
Recover DBs to IMS Recovey Expert RP
• Primary: Step 2: Clean Backup RECON
• IMS Recovery Expert Recon Clean Up (RCU)•Cleanup Timestamp
• Last DEALLOC or Stop Time of SLDS/RLDS•Closes open PRILOG, PRIOLD and SECSLD records•Deletes PRIOLD, SECOLD and SUBSYS records•Updates or deletes ALLOC and LOGALL records•Deletes IC and CA records past the Clean Up Time
• i.e… Automates the Recon clean up process
28
Recover DBs to IMS Recovey Expert RP
• Remote: Step 3: Recover DBs• Use Cleaned Up Recon to GENJCL.RECOV JCL• Recover DBs from ICs + CAs + SLDS/RLDS
+Change Accumulation
RLDS
SLDS
Image Copies
RECON
+ + RP
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Recover DBs to IMS Recovey Expert RP
• Step 4: Cold Start IMS• IMS RCU deletes all IMS Subsystem Records
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Storage Management Mirroring Disaster Recovery
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Storage Management Mirroring DR
• Mirroring DR Solutions• All Production volumes are mirrored to Remote Site• Mirroring can be Synchronous or Asynchronous
• Or, combination of two strategies• IMS can be Cold Started or Emergency Restarted
• Backouts occur during Emergency Restart• Consistency of Data is the key to mirroring• IBM Graphically Dispersed Parallel Sysplex (GDPS)
• Optional, helps automate the DR solution
32
Storage Management Mirroring DR
• Geographically Dispersed Parallel Sysplex (GDPS)• Manages:
• IBM Metro Mirror (PPRC)• IBM Global Mirror• IBM z/OS Global Mirror (XRC)
• Controls remote copy configuration and storage subsystem• Provides automation of sysplex operational tasks• Independent of applications like IMS and DB2• Includes IBM Services for configuration and manageability• Optional for Mirroring Solutions
33
Consistency of Data: Dependent Writes
• Committed Database Update
LOG
(1) Log “Before Image”
Good Sequence of Writes• (1)• (1) and (2)• (1), (2) and (3)
Bad Sequence of Writes• (1) and (3) only
(2) Update Database
Database
(3) Log “After Image”
LOG
34
Mirroring Environments
35
GDPS/PPRC… IBM Metro Mirror
– Synchronous DR Solution
– RPO is zero
– Emergency restart of IMS
– Automation and Freeze policy
– Duplexing of CF Structures okay
– Distances up to 300 km (with RPQ)
CF1
CF2
GDPSGDPSKK--syssys P1P1 P2P2
A
B
12
23
4567
8910
11 1
12
23
4567
8910
11 1
GDPSGDPSKK--syssys CBUCBU
Metro Mirror
K2
K1
Site 1
Site 2
OpenOpen
OpenOpen
36
GDPS/PPRC: Consistency
• (1) Consistency Group (CG)• Set of volumes hold IMS datasets and logs• When failure occurs for a volume in CG at
Remote Site• All writes in CG are held for period of time
• (2) GDPS Freeze Automation• FREEZE and GO:
• Writes continue at Primary even if failing at Secondary
• FREEZE and STOP:• Writes are frozen at Primary and Secondary
37
GDPS/Global Mirror
– Asynchronous DR Solution
– RPO can be 3 – 5 seconds (dependent on bandwidth)
– RTO - Emergency restart of IMS
– Local site response times are negligible
– Two site long distance DR and backup remote copy solution
CF1 GDPSGDPSKK--syssys P1P1 P2P2
A
12
23
4567
8910
11 1
K1
Site 1
Global Mirror
CF2GDPSGDPSRR--syssys P1P1 P2P2
B
12
23
4567
8910
11 1
R
Site 2
Backups
FRequired
FlashCopy
OpenOpen OpenOpen
38
GDPS/Global Mirror: Consistency
− (1) Primary creates Out-of-Sync Bit Maps:− Shows tracks with new data
− (2) Consistency Groups− FlashCopy is required for IBM Global Mirror
− FlashCopy is taken before changes are applied− Change Recording bitmap from Out-of-Sync bitmap
− Tracks in Change Recording bitmap are Updated
39
GDPS/XRC… z/OS Global Mirror
CF1 GDPSGDPSKK--syssys P1P1 P2P2
A
12
23
4567
8910
11 1
K1
Site 1
z/OS
Global Mirror
CF2P1P1 P2P2
B
12
23
4567
89
1011 1
SDM
Site 2
FOptional
FlashCopy
SDMSDM KxKx
Kx
– Asynchronous DR Solution
– RPO can be 3 – 5 seconds (dependent on bandwidth)
– RTO - Emergency restart of IMS
– Scales to any amount of DASD/distance
– z/OS Solution
40
GDPS/XRC: Consistency
− (1) Primary writes are timestamped − Timestamps are stored in Side File cache
− (2) System Data Mover (SDM)− Global Mirror uses SDM to “pull” data to Secondary− SDM uses timestamps in Side File to order writes− Consistency Group is journaled
41
GDPS/PPRC -- Global Mirror
Site 3
– Three site mirroring solution:–Metro Mirror for Site 1 & 2 –Global Mirror for site 2 & 3
– Site 2 RPO near 0– Site 3 RPO 3-5 secs if site 1 & 2 lost
CF1
CF2
GDPSGDPSKK--syssys P1P1 P2P2
A
B
12
23
4567
8910
11 1
12
23
4567
8910
11 1
GDPSGDPSKK--syssys CBUCBU
Metro Mirror
K2
K1
Site 1
Site 2
Global Mirror
CF3GDPSGDPSRR--syssys P1P1 P2P2
C
12
23
4567
8910
11 1
R BackupsOpenOpen
OpenOpen
42
GDPS/PPRC – XRC
Site 3
CF1
CF2
GDPSGDPSKK--syssys P1P1 P2P2
A
B
12
23
4567
8910
11 1
12
23
4567
8910
11 1
GDPSGDPSKK--syssys CBUCBU
Metro Mirror
K2
K1
Site 1
Site 2
z/OS
Global MirrorCF3P1P1 P2P2
B
12
23
4567
8910
11 1
SDM
SDMSDM KxKx
KxOpenOpen
OpenOpen – Three site mirroring solution:–Metro Mirror for Site 1 & 2 –z/OS Global Mirror for site 2 & 3
– Site 2 RPO near 0– Site 3 RPO 3-5 secs if site 1 & 2 lost
43
Coupling Facility Structures
• GDPS/PPRC• Primary and Secondary distance allows for Duplexing
• GDPS/Global Mirror, GDPS/XRC• Distance between sites usually prevents Duplexing• All CF structures are allocated during Emergency Restart
44
GDPS Metro Mirror: IMS CF Structures
• No Duplexing Needed:• OSAM and VSAM Buffer Pools
• Stored on DASD when data is committed• Secondary Site:
• All buffers are invalid and structure is rebuilt• IRLM Locks
• Secondary site:• Restart backs out inflight trans to release locks• IRLM rebuilds lock structure as empty
45
GDPS Metro Mirror: IMS CF Structures
• Good Candidate for Duplexing:• Shared Queues (MSGQ and EMHQ)• VTAM Generic Resources
• Structure changes infrequently• Rebuilding can take long time and users must wait
• Shared VSO• Store-In Structure:
• Committed updates on CF and not on DASD• Recover FP Areas after restart (if not duplexed)
• Two Duplexing options:• IMS Managed: IMS creates 2 structures/Area• System Managed (IMS V9+): Multiple Areas per
structure
46
Summary
• Two Disaster Recovery Strategies for IMS• IMS Application Dependent DR• Storage Management Mirroring
• IMS Application Dependent DR• Managing image copies, Recons, Logs at a Remote Site• IBM DM Tools can assist with this DR strategy
• Storage Management Mirroring• Production data is mirrored to Remote Site• Creating Consistency is the Key• Mirroring can be Asynchronous or Synchronous• GDPS can be used to automate DR strategy
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