Managing in-memory cache servers

Here you can find information on 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 more information about installing cache servers in a cluster, see Setting up 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 use an NTP daemon on each server synchronized to a common time source. For more information about NTP, refer to The NTP FAQ and HOWTO 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 by using the commands described here. Note that all cached data on that machine is 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.
To start a cache server, use 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 cache server machines

Adding a cache server to a cluster that has existing cache machines requires additional steps beyond a fresh installation. In particular, you 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. For more information, see Configuring Cache servers for high-availability.

To add a cash server to a cluster that has existing cache machines:

  1. Add the new cache server machine as follows:
    1. In the Admin Console, go to System > Settings > Caches.
    2. In Cache Servers, add the new cache server machine, then save the settings.
  2. Shut down every node in the cluster.
  3. Install the new cache server, as described in Setting up cache server.
  4. 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 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.
  5. Start up all cache servers before starting the application servers.

Removing cache server machines

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

Note: Having multiple cache servers is common only to high-availability configurations. For more information, see Configuring Cache servers for high-availability.

To remove a cache server machine from a cluster:

  1. Remove the cache server machine from the list as follows:
    1. In the Admin Console, go to System > Settings > Caches.
    2. In Cache Servers, remove the cache server machine, then save the settings.
  2. Shut down every node in the cluster.
  3. 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 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.
  4. 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.

Note: Having multiple cache servers is common only to high-availability configurations. For more information, see Configuring Cache servers for high-availability.

To move a cache server to another machine:

  1. Update the list of cache servers as follows:
    1. In the Admin Console, go to System > Settings > Caches.
    2. In Cache Servers, change the address for the cache server machine you're going to move, then save the settings.
  2. Shut down every node in the cluster.
  3. 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 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.
  4. Start up all cache servers before starting the application servers.