Managing In-Memory Cache Servers

This topic describes how you can manage the cache server nodes in a cluster. This includes starting and stopping servers, adding and removing nodes, and moving a node.

For information about installing cache servers in a cluster, see Setting Up a Cache Server.

Synchronizing Server Clocks

Cache servers determine the consistency of cached data between cache servers partially based on the timestamp used when storing and retrieving the data. As a result, all the clocks on all machines (both cache server machines and app server nodes) must be synchronized. It is common to do this through the use of an NTP daemon on each server synchronized to a common time source. You'll find a good starting point for understanding NTP at http://www.ntp.org/ntpfaq/. Note that clock synchronization becomes even more important when running within a virtualized environment; some additional steps may be required for proper clock synchronization as outlined in the vendor's documentation.

Also, if you're running in a virtualized environment, you must have VMware tools installed in order to counteract clock drift.

Starting and Stopping Cache Servers

You can start and stop cache servers using the commands described below. Note that all cached data on that machine will be lost when its cache server is shut down.

Note: If you're logged in as root, you can use su - jive to become the jive user.

Start a cache server using the following command as a jive user:

jive start cache

To stop a cache server use the following command as a jive user:

jive stop cache

Adding a Cache Server Machine

Adding a cache server to a cluster that has existing cache machines requires additional steps beyond a fresh installation. In particular, you'll need to shut down the entire cluster (both application and cache servers) before you add a new cache server.

Note: Having multiple cache servers is common only to high-availability configurations.

Before you shut down the cluster, add the new cache server machine. In the Admin Console, go to System > Settings > Caches. In the Cache Servers field, add the new cache server machine, then save the settings.
Shut down every node in the cluster.
Install the new cache server as described in Setting Up a Cache Server.
On each of the existing cache machines, set the cache machine addresses by typing jive set cache.hostnames list_of_hostnames as a jive user. You can use the a comma separated list of IP addresses or domain names, but be consistent with the format (use IP addresses or domain names, but not both) and order you use. For more on this and setting up cache servers for high-availability, see Configuring the Cache Servers for High-Availability.
Start up all cache servers before starting the application servers.

Removing a Cache Server Machine

Removing a cache server from an existing cluster is very similar to adding one.

Before you shut down the cluster, remove the cache server machine from the list. In the Admin Console, go to System > Settings > Caches. From the Cache Servers field, remove the cache server machine, then save the settings.
Shut down every node in the cluster.
On each of the existing cache machines, set the cache machine addresses by typing jive set cache.hostnames list_of_hostnames as a jive user. You can use the a comma separated list of IP addresses or domain names, but be consistent with the format (use IP addresses or domain names, but not both) and order you use. For more on this and setting up cache servers for high-availability, see Configuring the Cache Servers for High-Availability.
Start up all cache servers before starting the application servers.

Moving a Cache Server to Another Machine

Moving a cache server from an existing cluster is very similar to adding a machine.

Before you shut down the cluster, update the list of cache servers. In the admin console, go to System > Settings > Caches. In the Cache Servers field, change the address for the cache server machine you're going to move, then save the settings.
Shut down every node in the cluster.
On each of the existing cache machines, set the cache machine addresses by typing jive set cache.hostnames list_of_hostnames as a jive user. You can use the a comma separated list of IP addresses or domain names, but be consistent with the format (use IP addresses or domain names, but not both) and order you use. For more on this and setting up cache servers for high-availability, see Configuring the Cache Servers for High-Availability.
Start up all cache servers before starting the application servers.