Adding Logical Clusters

The logical cluster is an abstract representation of one or more instances in a physical shared-disk cluster used to manage workload, failover and client application access to the cluster.

1. Select Logical Cluster from the toolbar or right click on the Logical Clusters folder and select New Logical Cluster. The Adaptive Server plug-in starts the Logical Cluster wizard.
2. Name the logical cluster. Select a name that is representative of the job this logical cluster will perform. For example, SalesLC. Click Next.
3. Select the instances that make up the logical cluster.
   1. Select Add to see a list of available instances. The Add Instance to Logical Cluster window lists their instance name, ID, and state (whether it is online or offline). These instances are also known as the “base” instances.
   2. Select the instances you want to add. Hold the Control key down to select multiple instances. Click OK.
   3. Click Next.
   To remove an instance from this list, highlight its name and select Remove.
4. Add the failover server instances. These are instances on which the logical cluster will run if one or more of the base instances fail. Any instance in the physical cluster can be a failover resource. Workload management capabilities let you group and configure resources to specify failover order and precedence.
   1. Select Add for a list of available failover instances.
   2. The Adaptive Server plug-in displays the Add Failover to Logical Cluster window, which allows you to select:
      
      • The Failover Group – failover groups let you specify preference and order as to which failover instances are to be used. Lower-numbered groups are used first.

        Select the number for the failover group to which you want to associate these failover instances. Click OK.

      • The instance – the Add Failover Instance to Logical Cluster window lists the instances available to be failover instances.

        Select the instances. Hold the Control key down to select multiple instances. Click OK then click Next.

5. Add routed applications, logins, and aliases. Routing rules allow you to specify the logical cluster you want specific applications, logins, and aliases to connect to. See the Cluster Users Guide for more information about routing. The “Routed applications, logins, and aliases” window lists the Name and Type of currently defined routes. To add additional routes for:
   
   • Applications – select Add Application Route. Specify the name of the application in the Application Route window. Click OK.
   • Logins – select Add Login Route. Select the login name from the list in the New Login Binding window (hold the Ctrl key to select multiple names). Click OK.
   • Aliases – Select Add Alias Route. Specify the alias name in the Alias Route window. Click OK.

   To drop a listed route, select the route name and Click Drop Route. Click Next.

6. Define the options for the logical cluster (for more information about these options, see the “Managing the Workload” chapter of the Cluster Users Guide.
   
   • System view – an instance view means that monitoring and informational tools such as sp_who, sp_lock and monitoring tables display information only for the instance on which they are running. A cluster view means that they display information for all instances in the cluster.
   • Automatically start logical cluster – select this option to determine whether you want the logical cluster started when the cluster starts.
   • Failover mode – Select either “instance” or “group” from the drop-down list to specify whether you want the instances brought online as a group or individually.
   • Fail to any – specifies whether any instance can be a failover resource or only a specific instance can be a failover resource.
   • Down routing mode – specifies how client connections are routed if the logical cluster designated by the routing rule is not available. The options are:
     
     • system – sends un-routable connections to the system logical cluster.
     • open – sends unroutable connections to the open logical cluster.
     • disconnect – disconnects unroutable connections.

       See the Users Guide to Clusters for more information.

   • Logical cluster roles – select this option to indicate whether this logical cluster assumes an open role, meaning that all connections not routed to a logical cluster via an explicit routing rule are routed to the current open logical cluster. When you create a new cluster, the system logical cluster is automatically designated the open logical cluster. You can reassign the open role to another logical cluster. However, only one open logical cluster can exist per physical cluster.
   1. Click Next.
7. Select Finish to build the logical cluster.