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.

Start a cache server using the following command:
On Linux

/etc/init.d/jive-cache start 

To stop a cache server use the following command:

On Linux

/etc/init.d/jive-cache stop

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.

  1. 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.
  2. Shut down every node in the cluster.
  3. Install the new cache server as described in Managing Cache Servers.
  4. On each of the existing cache machines, edit the file at /etc/jive/conf/cache.conf and adjust the CACHE_ADDRESSES line to be identical to the list you entered on the new cache machine. You can use the IP address or domain name, but be consistent with the format you use. For more information, see Setting Up a Cache Server.
  5. 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.

  1. 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.
  2. Shut down every node in the cluster.
  3. On each of the existing cache machines, edit the file at /etc/jive/conf/cache.conf and adjust the CACHE_ADDRESSES line to remove the cache server machine.
  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.

  1. 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.
  2. Shut down every node in the cluster.
  3. On each of the existing cache server machines, edit the file at /etc/jive/conf/cache.conf and adjust the CACHE_ADDRESSES line to update the list so that it reflects the new list of machines, including the one you're moving.
  4. Start up all cache servers before starting the application servers.