13 Installing in High Availability Environments: OracleAS Disaster Recovery

13.2.1 Ensure Nodes Are Identical at the Operating System Level

Ensure that the nodes are identical with respect to the following items:

• The nodes are running the same version of the operating system.

• The nodes have the same operating system patches and packages.

• You can install Oracle Application Server in the same directory path on all nodes.

13.2.2 Set Up staticports.ini File

The same component must use the same port number on the production and standby sites. For example, if Oracle HTTP Server is using port 80 on the production site, it must also use port 80 on the standby site. To ensure this is the case, create a staticports.ini file for use during installation. This file enables you to specify port numbers for each component. Refer to Section 4.5.3, "Using Custom Port Numbers (the "Static Ports" Feature)" for details.

13.2.3 Set Up Identical Hostnames on Both Production and Standby Sites

The names of the corresponding nodes on the production and standby sites must be identical, so that when you synchronize data between the sites, you do not have to edit the data to fix the hostnames.

For the Infrastructure Nodes

For the node running the infrastructure, set up a virtual name. To do this, specify an alias for the node in the /etc/hosts file.

For example, on the infrastructure node on the production site, the following line in the hosts file sets the alias to asinfra:

138.1.2.111   prodinfra   asinfra

On the standby site, the following line sets the node's alias to asinfra.

213.2.2.110   standbyinfra   asinfra

When you install OracleAS Infrastructure on the production and standby sites, you specify this alias (asinfra) in the Specify Virtual Hostname screen. The configuration data will then contain this alias for the infrastructure nodes.

For the Middle-Tier Nodes

For the nodes running the middle tiers, you cannot set up aliases like you did for the infrastructure nodes because the installer does not display the Specify Virtual Hostname screen for middle-tier installations. When installing middle tiers, the installer determines the hostname automatically by calling the gethostname() function. You want to be sure that for each middle-tier node on the production site, the corresponding node on the standby site returns the same hostname.

To do this, set up a local, or internal, hostname, which could be different from the public, or external, hostname. You can change the names of the nodes on the standby site to match the names of the corresponding nodes on the production site, or you can change the names of the nodes on both production and standby sites to be the same. This depends on other applications that you might be running on the nodes, and whether changing the node name will affect those applications.

1. On the nodes whose local names you want to change, reconfigure the node so that the hostname command returns the new local hostname.

   
   

   Note: The procedure to change the hostname of a system differs between different operating systems. Contact the system administrator of your system to perform this step. Note also that changing the hostname of a system will affect installed software that has a dependency on the previous hostname. Consider the impact of this before changing the hostname.

   
   

2. Enable the other nodes in the OracleAS Disaster Recovery environment to be able to resolve the node using the new local hostname. You can do this in one of two ways:

   Method 1: Set up separate internal DNS servers for the production and standby sites. This configuration allows nodes on each site (production or standby) to resolve hostnames within the site. Before the internal DNS servers are the corporate, or external, DNS servers. The internal DNS servers forward non-authoritative requests to the external DNS servers. The external DNS servers do not know about the existence of the internal DNS servers. Refer to Figure 13-2.

   Figure 13-2 Method 1: Using DNS Servers

   
   Description of "Figure 13-2 Method 1: Using DNS Servers"
   
   

   Method 1 Details

   1. Make sure the external DNS names are defined in the external DNS zone. Example:

      prodmid1.us.oracle.com     IN  A  138.1.2.333
      prodmid2.us.oracle.com     IN  A  138.1.2.444
      prodinf.us.oracle.com      IN  A  138.1.2.111
      standbymid1.us.oracle.com  IN  A  213.2.2.330
      standbymid2.us.oracle.com  IN  A  213.2.2.331
      standbyinf.us.oracle.com   IN  A  213.2.2.110
      
      

   2. At the production site, create a new zone at the production site using a domain name different from your external domain name. To do this, populate the zone data files with entries for each node in the OracleAS Disaster Recovery environment.

      For the infrastructure node, use the virtual name or alias.

      For the middle-tier nodes, use the node name (the value in /etc/rc.config.d/netconf).

      The following example uses "asha" as the domain name for the new zone.

      asmid1.asha    IN  A  138.1.2.333
      asmid2.asha    IN  A  138.1.2.444
      asinfra.asha   IN  A  138.1.2.111
      
      

      Do the same for the standby site. Use the same domain name that you used for the production site.

      asmid1.asha    IN  A  213.2.2.330
      asmid1.asha    IN  A  213.2.2.331
      asinfra.asha   IN  A  213.2.2.110
      
      

   3. Configure the DNS resolver to point to the internal DNS servers instead of the external DNS server.

      In the /etc/resolv.conf file for each node on the production site, replace the existing name server IP address with the IP address of the internal DNS server for the production site.

      Do the same for the nodes on the standby site, but use the IP address of the internal DNS server for the standby site.

   4. Create a separate entry for Oracle Data Guard in the internal DNS servers. This entry is used by Oracle Data Guard to ship redo data to the database on the standby site.

      In the next example, the "remote_infra" entry points to the infrastructure node on the standby site. This name is used by the TNS entries on both the production and standby sites so that if a switchover occurs, the entry does not have to be changed.

      Figure 13-3 Entry for Oracle Data Guard in the Internal DNS Servers

      
      Description of "Figure 13-3 Entry for Oracle Data Guard in the Internal DNS Servers"
      
      

      On the production site, the DNS entries look like this:

      asmid1.asha        IN  A  138.1.2.333
      asmid2.asha        IN  A  138.1.2.444
      asinfra.asha       IN  A  138.1.2.111
      remote_infra.asha  IN  A  213.2.2.110
      
      

      On the standby site, the DNS entries look like this:

      asmid1.asha        IN  A  213.2.2.330
      asmid2.asha        IN  A  213.2.2.331
      asinfra.asha       IN  A  213.2.2.110
      remote_infra.asha  IN  A  138.1.2.111
      
      

   Method 2: Edit the /etc/hosts file on each node on both sites. This method does not involve configuring DNS servers, but you have to maintain the hosts file on each node in the OracleAS Disaster Recovery environment. For example, if an IP address changes, you have to update the files on all the nodes, and restart the nodes.

   Method 2 Details

   1. On each node on the production site, include these lines in the /etc/hosts file. The IP addresses resolve to nodes on the production site.

      
      

      Note: In the hosts file, be sure that the line that identifies the current node comes immediately after the localhost definition (the line with the 127.0.0.1 address).

      
      

      127.0.0.1    localhost
      138.1.2.333  asmid1.oracle.com   asmid1
      138.1.2.444  asmid2.oracle.com   asmid2
      138.1.2.111  asinfra.oracle.com  asinfra
      
      

   2. On each node on the standby site, include these lines in the hosts file. The IP addresses resolve to nodes on the standby site.

      
      

      Note: In the hosts file, be sure that the line that identifies the current node comes immediately after the localhost definition (the line with the 127.0.0.1 address).

      
      

      127.0.0.1    localhost
      213.2.2.330  asmid1.oracle.com   asmid1
      213.2.2.331  asmid2.oracle.com   asmid2
      213.2.2.110  asinfra.oracle.com  asinfra
      
      

   3. Ensure that the "hosts:" line in the /etc/nsswitch.conf file has "files" as the first item:

      hosts:   files nis dns
      
      

      The entry specifies the ordering of the name resolution. If another method is listed first, then the node will use the other method to resolve the hostname.

      
      

      Note: Restart the nodes after editing these files.

      
      

Verifying that the Nodes Resolve the Hostnames Correctly

After making the changes and restarting the nodes, check that the nodes resolve the hostnames properly by running the following commands:

• On the middle-tier nodes on both sites, run the hostname command. This should return the internal hostname. For example, the command should return "asmid1" if you run it on prodmid1 and standbymid1.

  prompt> hostname
  asmid1
  
  

• On each node, ping the other nodes in the environment using the internal hostname as well as the external hostname. The command should be successful. For example, from the first midtier node, prodmid1, run the following commands:

  prompt>  ping the production infrastructure node
  PING prodinfra: 56 data byes
  64 bytes from prodinfra.oracle.com (138.1.2.111): icmp_seq=0. time=0. ms
  ^C
  
  prompt>  ping the production infrastructure node
  PING iasinfra: 56 data byes
  64 bytes from iasinfra.oracle.com (138.1.2.111): icmp_seq=0. time=0. ms
  ^C
  
  prompt>  ping the second production midtier node
  PING iasmid2: 56 data byes
  64 bytes from iasmid2.oracle.com (138.1.2.444): icmp_seq=0. time=0. ms
  ^C
  
  prompt>  ping the second production midtier node
  PING prodmid2: 56 data byes
  64 bytes from prodmid2.oracle.com (138.1.2.444): icmp_seq=0. time=0. ms
  ^C
  
  prompt>  ping the first standby midtier node
  PING standbymid1: 56 data byes
  64 bytes from standbymid1.oracle.com (213.2.2.330): icmp_seq=0. time=0. ms
  ^C
  
  

13.2.4 If You Want to Use OracleAS Cold Failover Cluster on the Production Site

On the production site of a OracleAS Disaster Recovery system, you can set up the OracleAS Infrastructure to run in a OracleAS Cold Failover Cluster configuration. In this case, you have two nodes in a hardware cluster, and you install the OracleAS Infrastructure on a shared disk. Refer to Chapter 11, "Installing in High Availability Environments: OracleAS Cold Failover Cluster" for details.

Figure 13-4 Infrastructure in an OracleAS Cold Failover Cluster Configuration

Description of "Figure 13-4 Infrastructure in an OracleAS Cold Failover Cluster Configuration"

To set up OracleAS Cold Failover Cluster in this environment, use the virtual IP address (instead of the physical IP address) for asinfra.asha on the production site. The following example assumes 138.1.2.120 is the virtual IP address.

asmid1.asha          IN  A  138.1.2.333
asmid2.asha          IN  A  138.1.2.444
asinfra.asha         IN  A  138.1.2.120         this is a virtual IP address
remote_infra.asha    IN  A  213.2.2.110

On the standby site, you still use the physical IP address for asinfra.asha, but the remote_infra.asha uses the virtual IP address.

asmid1.asha          IN  A  213.2.2.330
asmid2.asha          IN  A  213.2.2.331
asinfra.asha         IN  A  213.2.2.110         physical IP address
remote_infra.asha    IN  A  138.1.2.120         virtual IP address

13.3.1 Installing the OracleAS Infrastructure

You must install the Oracle Identity Management and the OracleAS Metadata Repository components of OracleAS Infrastructure on the same node. You cannot distribute the components over multiple nodes.

The installation steps are similar to that for OracleAS Cold Failover Cluster. Refer to Section 11.3, "Installing an OracleAS Cold Failover Cluster (Infrastructure) Configuration" for the screen sequence. Note the following points:

• Select Configuration Options screen: Select High Availability and Replication. Refer to Table 11-2, step 9.

• Specify Virtual Hostname screen: Enter an alias as the virtual address (for example, asinfra.oracle.com). Refer to Table 11-2, step 13.

13.3.2 Installing Middle Tiers

You can install any type of middle tier that you like:

For installing J2EE and Web Cache, see Section 7.9, "Installing J2EE and Web Cache in a Database-Based Farm Repository and with Oracle Identity Management Access".

For installing Portal and Wireless or Business Intelligence and Forms, see Section 7.13, "Installing Portal and Wireless or Business Intelligence and Forms".