Episode 3 DB2 pureScale Availability And Recovery [Read Only] [Compatibility Mode]
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DB2 pureScale provides high availability and continuous operations by automatically recovering from component failures through workload redistribution and fast in-flight transaction recovery. It protects databases by balancing workloads across nodes and uses duplexed secondary components to tolerate multiple simultaneous node failures while keeping other nodes online and services available.
Episode 3 DB2 pureScale Availability And Recovery [Read Only] [Compatibility Mode]
- 1. DB2 pureScale Availability & Recovery © 2010 IBM CorporationOctober 13, 2010 Aamer Sachedina (aamers@ca.ibm.com) Kelly Schlamb (kschlamb@ca.ibm.com)
- 2. Information Management Continuous Availability Protect from infrastructure outages Automatic workload balancing Duplexed secondary global lock © 2009 IBM Corporation2 Automatically recovers from component failures Tolerates multiple node failures Duplexed secondary global lock and memory manager
- 3. Information Management DB2 Cluster Services Overview DB2DB2 DB2 DB2 DB2 Integrated DB2 component Single install as part of DB2 installation Upgrades and maintenance through DB2 fixpack © 2009 IBM Corporation3 C F DB2 Cluster Services: Cluster File System (GPFS) DB2 Cluster Services: Cluster Manager (RSCT) Cluster Automation (Tivoli SA MP) DB2DB2 DB2 DB2 DB2 C F
- 4. Information Management DB2 Cluster Services DB2 Cluster Services Reliable Scalable Cluster Technology Tivoli Systems Automation for Multi-Platforms IBM General Parallel File System © 2009 IBM Corporation4 DB2 CS tightly integrates these IBM products into DB2 pureScale DB2 instance creation creates RSCT and GPFS domains across hosts Single command used to add hosts to the instance: db2iupdt –add -m newhost.acme.com db2inst1
- 5. Information Management DB2 pureScale HA Architecture Member DB2 CS Member DB2 CS Member DB2 CS Member DB2 CS © 2009 IBM Corporation5 Cluster Interconnect GPFS 2nd-ary CS CS Primary Secondary
- 6. Information Management Application Servers and DB2 Clients Virtually Instantaneous Recovery From Node Failure Protect from infrastructure related outages – Automatically redistribute workload to © 2009 IBM Corporation6 redistribute workload to surviving nodes – Automatically recover in-flight transactions in as little as 15-20 seconds including detection of the problem
- 7. Information Management Minimize the Impact of Planned Outages Bring node Keep your system up – During OS fixes – HW updates – Administration © 2009 IBM Corporation7 Identify MemberDo Maintenance Bring node back online
- 8. Information Management Member Hardware Failure Clients Power cord tripped over accidentally DB2 Cluster Services looses heartbeat and declares member down – Informs other members & CF servers – Fences member from logs and data – Initiates automated member restart on another (“guest”) host > Using reduced, and pre-allocated memory model – Member restart is like a database crash recovery in a single system database, but is much faster • Redo limited to inflight transactions (due to FAC) • Benefits from page cache in CF In the mean-time, client connections Single Database View Automatic; © 2009 IBM Corporation8 Log CS CS DB2 Shared Data In the mean-time, client connections are automatically re-routed to healthy members – Based on least load (by default), or, – Pre-designated failover member Other members remain fully available throughout – “Online Failover” – Primary retains update locks held by member at the time of failure – Other members can continue to read and update data not locked for write access by failed member Member restart completes – Retained locks released and all data fully available CS DB2 CS DB2 CS Updated Pages Global Locks LogLogLog PrimarySecondary Updated Pages Global Locks CS DB2 DB2 Ultra Fast; Online Almost all data remains available. Affected connections transparently re-routed to other members.
- 9. Information Management Member Failback ClientsPower restored and system re- booted DB2 Cluster Services automatically detects system availability – Informs other members and Single Database View © 2009 IBM Corporation9 Log CS CS DB2 Shared Data – Informs other members and PowerHA pureScale servers – Removes fence – Brings up member on home host Client connections automatically re-routed back to member CS DB2 CS CS Updated Pages Global Locks LogLogLog PrimarySecondary Updated Pages Global Locks CS DB2 DB2 DB2
- 10. Information Management Member Hardware Failure and Failback > db2instance -list ID TYPE STATE HOME_HOST CURRENT_HOST ALERT 0 MEMBER STARTED host0 host0 NO 1 MEMBER STARTED host1 host1 NO 2 MEMBER STARTED host2 host2 NO 3 MEMBER STARTED host3 host3 NO 4 CF PRIMARY host4 host4 NO 5 CF PEER host5 host5 NO DB2 DB2 DB2 DB2 host1host0 host3host2 > db2instance -list ID TYPE STATE HOME_HOST CURRENT_HOST ALERT 0 MEMBER STARTED host0 host0 NO 1 MEMBER STARTED host1 host1 NO 2 MEMBER STARTED host2 host2 NO 3 MEMBER RESTARTING host3 host2 NO 4 CF PRIMARY host4 host4 NO 5 CF PEER host5 host5 NOCS > db2instance -list ID TYPE STATE HOME_HOST CURRENT_HOST ALERT 0 MEMBER STARTED host0 host0 NO 1 MEMBER STARTED host1 host1 NO 2 MEMBER STARTED host2 host2 NO 3 MEMBER WAITING_FOR_FAILBACK host3 host2 NO 4 CF PRIMARY host4 host4 NO 5 CF PEER host5 host5 NO © 2009 IBM Corporation10 5 CF PEER host5 host5 NO HOST_NAME STATE INSTANCE_STOPPED ALERT host0 ACTIVE NO NO host1 ACTIVE NO NO host2 ACTIVE NO NO host3 ACTIVE NO NO host4 ACTIVE NO NO host5 ACTIVE NO NO 0 host0 0 - MEMBER 1 host1 0 - MEMBER 2 host2 0 - MEMBER 3 host3 0 - MEMBER 4 host4 0 - CF 5 host5 0 - CF db2nodes.cfg Shared Data host4 PrimarySecondary 5 CF PEER host5 host5 NO HOST_NAME STATE INSTANCE_STOPPED ALERT host0 ACTIVE NO NO host1 ACTIVE NO NO host2 ACTIVE NO NO host3 INACTIVE NO YES host4 ACTIVE NO NO host5 ACTIVE NO NO Log DB2 CS LogLogLog DB2 5 CF PEER host5 host5 NO HOST_NAME STATE INSTANCE_STOPPED ALERT host0 ACTIVE NO NO host1 ACTIVE NO NO host2 ACTIVE NO NO host3 INACTIVE NO YES host4 ACTIVE NO NO host5 ACTIVE NO NO host5 Shared Data
- 11. Failure Mode DB2 DB2 DB2 DB2 CF CF Member Other Members Remain Online ? Automatic & Transparent ? Comments Only data that was in- flight on failed member remains locked temporarily. Connections to failed member transparently Summary : Single Failure DB2 DB2 DB2 DB2 CF CF DB2 DB2 DB2 DB2 CF CF Primary CF Secondary CF member transparently move to another member Momentary “blip” in CF service. Transparent to members (In-flight CCF requests just take a few more seconds before completing normally.) . Momentary “blip” in CF service. Transparent to members (In-flight CF requests just take a few more seconds before completing normally.) .
- 12. DB2 DB2 DB2 DB2 CF CF Failure Mode Other Members Remain Online ? Automatic & Transparent ? Comments Only data that was in- flight on failed members remains locked temporarily. Recoveries done in parallel.Connections to failed member transparently Summary : Multiple Failures DB2 DB2 DB2 DB2 CF CF DB2 DB2 DB2 DB2 CF CF . Same as member failure. Momentary, transparent, “blip” in CF service. . . Same as member failure. Momentary, transparent, “blip” in CF service. . member transparently move to another member Connections to failed member transparently move to another member Connections to failed member transparently move to another member