7.2 Cluster Support

This section provides the following:

7.2.1 Clustering in NetWare 6.0

In NetWare 6.0, you deployed older versions of DNS servers in a clustered environment and configured a DNS server on each of the nodes in the preferred node list corresponding to the resource. If the current node failed, the DNS server migrated from the current node to another node, depending on the sequence of nodes in the preferred node list. The number of DNS server objects equaled to the number of nodes in the preferred node list.

Although older versions of DNS servers supported clustering, it was limited to starting a DNS server and had its own identity. This server identity was different from the DNS server running on the next node.

For example, consider the following scenario:

  • The preferred node list has Node 1, Node 2, and a designated primary DNS server (DNS server object 1) running on Node 1. This DNS server is supposed to handle the dynamic updates received from the DHCP server.
  • An outage happens on Node 1 and the DNS server migrates to Node 2.
  • Node 2 uses another DNS server (DNS server object 2), which is not a designated primary DNS server. It cannot handle the dynamic updates, so the identity of the DNS server is lost during a node outage.

For more information about cluster services, see the OES Novell Cluster Services 1.8 Administration Guide for NetWare.

7.2.2 Clustering in NetWare 6.5

In a clustered environment, the new DNS server, by default, supports the functionality provided by the older versions of DNS server. In addition, you can configure a new DNS server to maintain its identity after a node outage. In such case, only one DNS server is required per failover path (preferred node list) instead of one DNS server per node, as was the case with the older versions of DNS server.

7.2.3 Creating a Cluster-Enabled DNS Server

Consider the following scenario for an existing DNS server:

  • The old DNS server is running in a cluster with one DNS server per node in the preferred node list. For any set of zones, only one of these can be a designated DNS server and the rest are passive DNS servers.
  • A second DNS server running without a cluster.

To migrate this setup, you must consider the following points if you want the DNS server to take advantage of the new functionality and maintain its identity after an outage:

  • All NCP™ servers in the preferred node list should be upgraded to NetWare 6.5.
  • DNS server objects should not be created on an NCP server that is part of any existing preferred node list.
  • Before moving any server, the DNS server should be brought down.
  • Any node that is considered as a potential candidate to host DNS Services should be part of the only preferred node list.

You must also decide the following:

  • Identify the DNS server object that has to be retained from the DNS servers corresponding to all nodes in the preferred node list. All other DNS server objects must be removed.
  • If you want to retain all DNS server objects, create a separate failover path for every DNS server object.

7.2.4 Configuring a DNS Server in a Clustered Environment

  1. Make sure that the server has been upgraded to NetWare 6.5.

  2. Run nwdeploy.exe from the root of the NetWare 6.5 Operating System CD to upgrade the cluster software.

  3. Launch ConsoleOne.

  4. Create a Virtual NCP server by making a shared volume as cluster-enabled.

  5. Identify the Volume Resource corresponding to the Virtual NCP server object.

    A Virtual NCP server object has a reference to the Volume Resource in the attribute Resources.

  6. Verify the load script in the volume resource as follows:

    add secondary ipaddress xxx.xxx.xxx.xxx
    
    load named -v volume name
    

    where xxx.xxx.xxx.xxx is the IP address of the Netware server.

  7. Verify the unload script in the volume resource as follows:

    unload named
    
    del secondary ipaddress xxx.xxx.xxx.xxx
    
  8. Configure the desired policies for startup, failover, and failback in the Policies tab.

  9. Select the Nodes tab and specify the desired available nodes and node preference order.

  10. Launch any of the DNS/DHCP management utilities.

  11. Click Create > DNS Server in the Java-based Management Console

    or

    Click Create DNS Server from the iManager roles.

  12. Select the Virtual NCP server object created in Step 4.

  13. Provide other inputs to create the DNS server, then click OK.

In order to make an existing non-cluster-enabled DNS server support clustering, use the move DNS server feature as follows:

  1. Upgrade the server to NetWare 6.5.

  2. Launch one of the DNS/DHCP management utilities.

  3. Identify the NCP server and the corresponding DNS server object that should be retained.

    Make sure that the DNS Services is not running on this NCP server.

  4. Identify the Virtual NCP server where DNS Services will be based.

    Unlike old DNS servers that were cluster-enabled as a cluster resource, this should be cluster-enabled as a volume resource corresponding to the shared volume. Do this with the ConsoleOne snap-ins for Clustering Services.

  5. Make sure that none of the nodes in the preferred node list has an associated DNS server (except the NCP server selected in Step 4 if it is part of the preferred node list).

    Do this by deleting all other DNS servers in the preferred node list or moving them out of the preferred node list.

  6. Use one of the DNS/DHCP management utilities to move the DNS server from the NCP server identified in Step 3 to the Virtual NCP server identified in Step 4.

For more information, see Moving a DNS Server and Moving a DNS Server.

Adding a Node to a Cluster-Enabled DNS Server

To add a new node to the preferred node list of a DNS server that has been configured to maintain its identity across outage:

  1. Make sure that each new node has been successfully added to the preferred node list.

  2. Using ConsoleOne, add a reference to the corresponding physical NCP server to the group object's Members and EquivalentToMe list for each newly added node.

Alternatively, you can temporarily move the DNS server to another NCP server, and then move it back to the original NCP server.

After the DNS server has been created or moved to a Virtual NCP server, you can start the DNS server by doing the following:

  1. Launch ConsoleOne.

  2. Select the Netware Cluster object.

  3. Click View > Cluster State to change to the cluster state view.

  4. Click the DNS Cluster Resource to start the Resource Manager.

  5. Click Online to start the resource.

  6. Configure your clients to use the new resource as their primary DNS server.

    We recommend that you configure your DHCP server to pass this name server address to clients by using DHCP.

All the entities that require the IP address of the DNS server should be configured with the secondary IP address of the virtual NCP server.

7.2.5 Deleting Empty Resource Records

A new command line utility (dnsmaint.nlm) that supports deletion of empty RRs that have accumulated over time, is introduced in NetWare® 6.5SP3 release.

This utility must be executed on a NetWare 6.5 SP3 machine in the eDirectory tree. The usage of the utility is specified below.

dnsmaint -User [-Password] [-Zonelist] [-LocatorObject] [-NotUsedSince]

The command line options are listed in the table below:

Options

Description

-User

Refers to the FQDN of the eDirectory user.

-Password

eDirectory password of the user. Can be passed either as a command line parameter or can be entered later at the password prompt, when the utility is run.

-ZoneList

eDirectory FDQNs of the list of zones to be processed. Replace all occurences of dot '.' in zone name with underscore '_'.

Zone names must be separated by a semicolon(;).

If this option is missing, LocatorObject must be specified.

-LocatorObject

eDirectory FQDN of the DNS locator object.

This option must be used only if -Zonelist option is not specified.

-NotUsedSince

Empty RR's not used since the specified number of days are deleted.

By default all the empty RRs are deleted.

Any number between 1 and 360 can be used.

Examples:

For all the samples, it is assumed that the eDirectory distinguished name of DNS locator object is dns-dhcp.novell.

  • To delete all the empty Rrs from all the zones in the eDirectory tree.

    dnsmaint -User:admin.novell -Password:novell -LocatorObject:.dns-dhcp.novell

  • To delete all the empty RRs not used since 3 days, from all the zones.

    dnsmaint -User:admin.novell -Password:novell -LocatorObject:.dns-dhcp.novell -NotUsedSince:3

  • To delete all empty RRs from the zone blr.novell.com which is under eDirectory context dns-zones.

    dnsmaint -User:admin.novell -Password:novell Zonelist:blr_novell_com.dns-zones

    NOTE:All the ‘.’ (dots) in the zone name blr.novell.com are replaced with ‘_'(underscores).

  • To delete empty RRs not used since 5 days from the zone 155.72.143.IN-ADDR.ARPA which is under eDirectory context novell.

    dnsmaint -User:admin.novell -Password:novell -Zonelist:155_99_164_IN-ADDR_ARPA.novell -NotUsedSince:5