This optional procedure sets up node replication to provide
high availability and fail-over support for the cluster. If one member
of the cluster goes down, other nodes can continue to process the
SIP request. Use this procedure only if you require high availability
and fail-over support.
Before you begin
Before you begin, you must install IBM® Sametime® Gateway
on each node, add the nodes to a cluster, and then start the cluster
and the SIP proxy server. Enabling high availability uses additional
memory which reduces your server's session capacity. For more information
about enabling high availability, see the IBM Sametime Gateway
sizing guide in the Sametime wiki:
Sametime Gateway
8.5.0 and 8.5.1 sizing guidelines
About this task
Sametime Gateway
offers a comprehensive high availability (HA) solution. High availability
means an environment that doesn't have a single point of failure,
and therefore prevents the users from loosing presence awareness in
the event of a Gateway server instance failure.Replication domains
A
SIP cluster with replication and failover can consist of many server
instances. Each replication domain contains a set of two servers.
Therefore, the number of replication domains needed is half the number
of server instances. You need to create a new replication domain for
each pair of Sametime Gateway
instances (deployment manager and proxy server do not count). For
example: if you have eight Sametime Gateway instance,
you will be creating four replication domains. In case one server
instance fails, the remaining server instance begins servicing the
replicated SIP sessions of the failed instance. Therefore, IBM recommends that you pair server
instances that are NOT likely to fail at the same time. For example,
you should not pair server instances if both are running on the same
physical host.
Procedure
- Validate that the environment is ready:
- Click and verify that the Sametime Gateway cluster
is started and the status is green.
- Click and verify that
the SIP proxy is started and the status is green.
- Click and verify that the specified cluster
is the same Sametime Gateway
cluster defined in the previous step.
- Create your new replication domains:
- Click , and then
click New. Note: Disregard the GatewayCache.
This is the DynaCache used to propagate the configuration across the
cluster, and is not used for SIP session replication.
- Type a name for the new replication domain. For example: SIPRD1.
- In the Number of Replicas section,
select Entire Domain so that the SIP session
is replicated to both Gateway instances, and click OK.
- Repeat this process for each replication domain you
wish to create.
- Assign replication domains to server instances:
- Click , and then
select a member of the cluster.
- In the "Container Settings" section, click Session
management.
- In the "Additional Properties" section, click Distributed
environment settings.
- In the "Distributed sessions" section, click Memory-to-memory
replication. The distributed session option will become
enabled once configured.
- In the "Replication domain" section, select one of the
replication domains that you created in previous steps. Remember,
each replication domain must be assigned to exactly two server instances.
- In the Replication mode field,
select Both client and server, then click OK,
and Save. Memory to memory replication is now
enabled for this member of the cluster.
- Repeat the previous step for each member of the cluster.
- When High Availability is configured, you may see redundant
SIP Container printouts in the log files, such as these:
[6/7/11 18:34:45:409 IDT] 0000006d RepCommand I RepCommand _replication updates=2 removes = 1 in the last 1439735 milliseconds
[6/7/11 18:57:45:321 IDT] 0000006d RepCommand I RepCommand _replication updates=4 removes = 2 in the last 1379911 milliseconds
Add
a SIP Container custom property to suppress these messages:
- Click .
- Click the Gateway server (for example, GWServer1).
- Select SIP Container in the section.
- Select Custom properties in the
"Additional Properties" section.
- Click New to add a new custom
property.
- Give the property the following name and value:
Name: enable.replication.debug.mode
Value: false
- Click OK.
- Update the master configuration by clicking Save in
the "Messages" box at the beginning of the page.