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IBM Integration Bus
High Availability Overview
Peter Broadhurst
IBM Messaging & Integration

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© 2013, 2014 International Business Machines Corporation 2
Introduction
These charts provide a high-level overview of IIB HA topologies:
• Comparison of active/active and active/passive HA
• Solutions for active/passive HA failover with IBM Integration Bus
• Solutions for active/active processing with IBM Integration Bus
• Adding Global Cache to active/active processing
• Combining all of the above
Only HTTP and JMS (MQ) workloads are shown

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Active/active vs. active/passive
Scale High Availability Design Considerations
Active/Active All N instances contribute to
the processing capacity of
the system
New requests can be serviced
immediately after the planned
or unplanned termination of
an active instance.
Often referred to as
continuous availability.
Each instance must be able to
operate independently, without
relying on the availability of any
other instance in the environment.
The order of processing for two
items of work cannot be
guaranteed, as there are multiple
instances that might perform each
item of work
Active/Passive Only one of N instances
contributes to the processing
capacity of the system
There is a failover period after
the planned or unplanned
termination of an active
instance. This failover period
commonly lasts for a small
number of minutes,
depending on the technology
used.
An infrastructure for HA failover
must exist, that ensures only one
instance is ever activated, as well
as detecting when one instance
fails to initiate the failover.
The active and the passive
system must have identical copies
of persistent data, such as
persisted transaction state, and
persisted messages. In IBM
Integration Bus this is achieved by
sharing a filesystem between the
two machines.

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© 2013, 2014 International Business Machines Corporation 4
Active/passive high availability
Machine 1 Machine 2
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
Shared
file system
HA
failover
• Single instance of the IIB runtime
• Single instance of all state
– Configuration, MQ messages and Transaction coordinator
• Highly available due to automatic fail-over. Two options available for HA failover:
– Out-of-the-box with Multi-Instance capability,
– Or using external HA cluster software
JMS workloads
HTTP workloads

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Option 1: Out of the box Multi-Instance failover
• IP address of each machine is different
– IP address redirect is required for HTTP workloads
– MQ client libraries automatically handle IP redirect for JMS workloads
• Requires highly available network-attached storage (NAS). Examples:
– IBM GPFS
– Veritas Cluster File System
– Highly available NFSv4
• More information on choosing a suitable NAS:
– https://ibm.biz/BdFxfz
Machine 1 – IP addr 1 Machine 2 – IP addr 2
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
Network-
attached
file system (NAS)
TCP/ IP
Failover
managed
via
NAS file
locks
IP redirect (Gateway / Load Balancer)
JMS workloads
TCP/ IP

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Option 2: HA cluster failover
• Allows use of direct-attached storage
• IP address failed over by HA cluster software
• Requires HA cluster software. Examples:
– IBM PowerHA (HACMP)
– Veritas Cluster Server (VCS)
– Microsoft Cluster Service (MSCS)
– Red Hat Cluster
Machine 1 – IP addr 1 Machine 2 – IP addr 1
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
Direct-attached
file system
switched by HA
Failover
managed
via
health
checking
Fibre/SCSI
HA cluster Software HA cluster Software
Heartbeat
Healthcheck Healthcheck
JMS workloads
HTTP workloads
Fibre/SCSI
IP addr
failover

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Multi-instance or HA cluster?
Multi-instance queue manager
• Integrated into the IIB and MQ products
• Faster failover than HA cluster*
• Delay before queue manager restart is much shorter*
• Runtime performance of networked storage must be considered
• IP address of standby instance is different to primary
• No automatic fail-back to primary hardware when restored
• More susceptible to MQ and OS defects
HA cluster
• Capable of handling a wider range of failures
• Failover historically rather slow, but some HA clusters are improving
• Some customers frustrated by unnecessary failovers
• Require MC91 SupportPac or equivalent configuration
• Extra product purchase and skills required
Storage distinction
• Multi-instance queue manager typically uses NAS
• HA clustered queue manager typically uses SAN
*depends on NAS file-system tuning and specific customer environment

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Active/active topologies
Machine 1 Machine 2
IIB Integration Node
MQ Messaging
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
WESB AppTargetWESB AppTargetIntegration Server
Gateway / Load Balancer for HTTP workloads
HTTP workloads
JMS workloads
• Each Integration Node operates independently
• Continuous availability of the service during a failure
– Individual in-flight requests on the failed node receive errors, but the service stays available
• HTTP workloads require external workload balancing
– Hardware load balancer is the most common solution
• JMS workloads require load balancing
– Via an MQ cluster when remote applications have their own MQ queue managers
– Options for direct MQ client attachment (over TCP/IP) described here: https://ibm.biz/BdFxfS

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Adding Global Cache to active/active topologies
Machine 1 Machine 2
IIB Integration Node
MQ Messaging
Global
Cache
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
WESB AppTargetWESB AppTargetIntegration Server
• Highly available in-memory state store
– High performance compared to disk persistence (DB/MQ Messaging)
– High availability through redundancy – cannot be recovered if all nodes are stopped concurrently
– Built with WebSphere eXtreme Scale technology
• Alternative to using MQ or a Database for state storage/retrieval
– Correlation state between asynchronous request/reply flows
• Only needed if replies might be routed via a different runtime, otherwise simply use memory (LocalEnvironment etc.)
– Regularly accessed reference data, such as routing tables

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Global
Cache
Putting it all together
• Active/active processing. HA fail-over for state and in-flight message recovery
• Individual queues/flows can be configured active/passive if required
– Single flow instance for message ordering or file-based processing
– Single correlation state queue shared between active flow instances
Machine 1 Machine 2
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
IIB Integration Node
MQ Messaging
WESB AppTargetWESB AppTargetIntegration Server
Shared
Filesystem
Failover
Failover
Gateway / Load Balancer for HTTP workloads
JMS workloads
HTTP workloads

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More information
• Knowledge Center starting points:
IIB Active/passive HA: https://ibm.biz/BdFxfe
IIB Active/active HA for HTTP: https://ibm.biz/BdFxfb
IIB Global cache: https://ibm.biz/BdFxfp
MQ HA Cluster configurations: https://ibm.biz/BdFxf8
• Wiki article with detailed description of IIB topology choices
Tailored to customers migrating from WebSphere WESB, but useful to all
https://ibm.biz/BdFxfa
• MQDev blog on attaching MQ clients to active/active qmgrs:
https://ibm.biz/BdFxfS
• Testing and support statement for multi-instance
https://ibm.biz/BdFxfz