Slides from episode 3 of the recent DB2 pureScale webcast series with the IBM Lab team.

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