Netscape Application Server-- Managing Distributed Data Synchronization

Administration Guide
Overview Guide
Installation Guide


Modifying the Default Cluster for Fast Cluster Set Up
The fastest and easiest way to set up a cluster is to set the cluster up when you install the Netscape Application Servers. After installation, the easiest way to set up a cluster is to modify the Default cluster that was automatically created when the Netscape Application Server was installed. Cluster Tasks Through the GUI After a cluster has been set up, you can easily edit some of the cluster properties through the Netscape Application Server Administrator. The section "Using Netscape Application Server Administrator to Configure Clusters" describes how to perform the following actions through the GUI. Add a server to a cluster Remove a server from a cluster Change a server's Sync Server priority Modify the maximum number of Sync Backups You can also perform these tasks and more by editing the registry, as described in all other task-oriented sections in this chapter. About the Default cluster If a cluster is not set up during installation, the installation program creates a default cluster, named Default, for the Netscape Application Server. At installation, the SyncServers registry key for the Default cluster lists only one server—the server, itself. So the Default cluster contains all that a cluster needs to be complete and active except for the new name for the cluster and the names of all Sync Servers with which to synchronize. Because the Default cluster already contains all the registry keys that a cluster needs, you can easily set up a cluster by making a few substitutions in the registry keys for the Default cluster. If you were creating a completely new cluster, you would have to create the registry keys for that new cluster. Start with a Sync Server Start your editing of Default registry keys on a server that will be a Sync Server. Then, after you set up one registry for your cluster, make sure that the relevant registry keys of all servers in the cluster are identical to the keys that you first edited. Be Sure to Remove Sync Locals From the Cluster To make the keys identical, remove the identification and priority information for each Sync Local from its own cluster. Sync Locals are never listed in the SyncServers registry key for a legitimate cluster. But, because each Sync Local is automatically listed in its own Default cluster, you must remove each Sync Local from its own SyncServers key. This necessity will be obvious if the registry you first edit belongs to a Sync Server, and you then match all other cluster registries to your original. IP Addresses Can Be Found in the SyncServers Key When you edit the SyncServers registry for the Default cluster, you will enter the IP address for each of the Sync Servers in your cluster. At installation, the IP address for each Netscape Application Server is placed in the SyncServers registry key of that server's Default cluster. When you enter the address for each Sync Server into the first SyncServer registry key, remember that you can find the information in the registry for each server. Note, however, that you will remove this entry on each Sync Local. If you decide later to promote a Sync Local to a Sync Server, you will have to find the address information elsewhere. Editing the Registry Keys for the Default Cluster Stop the Netscape Application Server whose registry you will edit. Be aware that editing the server registry while the server is running can cause serious problems. Also, some changes take effect only after the engine is recycled. Open the registry editor. On a UNIX system, type kregedit at the command prompt. On a Windows NT system, type kregedit or regedit either in the Run item of the Start menu or at the MS-DOS prompt. Both kregedit and regedit bring up the regedit application. The registry editor displays the keys and values that apply to the Netscape Application Server. The appearance varies slightly between the UNIX and Windows NT systems. Open the registry folder. On a UNIX system, open Kiva\\Enterprise\\2.0\\Clusters. On a Windows NT system, open the folder HKEY_LOCAL_MACHINE\\SOFTWARE\\KIVA\\Enterprise\\2.0\\Clusters As you proceed through each of the steps in this procedure, you can refer to the following figure that shows the kregedit display on a UNIX system. In this example, the Default cluster has been renamed "QA" and, so far, contains one Sync Server with a priority of zero. This same information appears in regedit on a Windows NT system, but in two side-by-side windows. KIVA\\Enterprise\\2.0\\Clusters\\QA\\SyncServers Whenever one of the following steps directs you to modify a registry name or value, you can modify that name or value by Double-clicking on the key name to bring up a pop-up window Entering the new name or value in the pop-up window Clicking OK to dismiss the pop-up window Ignore the SyncPersChunkSz value. This key relates to an unsupported feature and is now ignored by the server. If this key should somehow get removed, don't worry—its presence is no longer necessary. Check and modify the SyncTimerInterval value, as necessary. This key specifies the intervals, in seconds, at which the synchronization service wakes up and checks to see whether any data has expired. Specifically, this key specifies how often the timer thread goes through the node list and removes all the nodes that have expired. If this value is too large, expired data will still be accessible. If this value is too small, the frequent waking up and checking can degrade system performance. The default value of 60 seconds is good for most clusters. Change the name "Default" to a new, unique name for your cluster ("QA" in the example). Check and modify the MaxBackups value, as necessary. The maximum number of backup data synchronization servers determines how many Sync Backups are updated with data from the Sync Primary at the same time. For more information about backup data synchronization servers, see "What is a Cluster?" Because all Sync Backups are updated at the same time, an extra load is created for each additional backup server. Consider the performance impact when you set the number of backups, and try to choose a number that is high enough to provide safety, while not so high as to negatively affect performance. The default value of 1 (one) is usually sufficient. Ignore the MaxHops key. This key relates to an unsupported feature and is now ignored by the server. If this key should somehow get removed, don't worry—its presence is not necessary. Add each Sync Server to the cluster under SyncServers. The IP addresses and port numbers under the SyncServers key are the Executive Server processes of the Netscape Application Servers that belong to this cluster. Each server is listed by its host IP address:KXS port number=priority level. For a possibly helpful tip on finding the IP address and port number, see "IP Addresses Can Be Found in the SyncServers Key." Add the IP address and port number for the Sync Server. Set the priority for each Sync Server by double-clicking the priority value to bring up a pop-up window, entering the priority number, and clicking OK. The IP address, port number, and priority for the Sync Server whose registry you are editing should have been listed under the SyncServers key at installation. The priority setting for a data synchronization server determines which Sync Backup in a group of Sync Backups will become the replacement Sync Primary, and which Sync Alternate in a group of Sync Alternates will become the replacement Sync Backup. Priority settings start at zero, the highest priority setting. The lowest priority is 65,535. For more information about priority, see "How Sync Server Priority Affects a Cluster." Close the registry editor when you're finished. Repeat the procedure for each server in the cluster until the registry keys under Clusters are identical, with all Sync Servers listed in the same order in each SyncServers key. After correctly completing these steps, you have redefined the Default cluster. Now, follow the procedure in "Mapping the Synchronizer to the Cluster" to enable communication between the servers in the cluster.