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HA-OSCAR: Five Steps to a High-Availability Linux Cluster
Pages: 1, 2, 3, 4

Configuring the Standby Server

The third step requires the you to enter an alias public IP address. Proceed by clicking on step 3. HA-OSCAR will pop up the Standby server initial network Configuration screen shown in Figure 5. Users normally use this public IP address as a virtual entry point to access the head node. When the failover occurs, the standby server will take over this address so users can continue accessing the cluster as if nothing has happened. The normal procedures within this step are:

  1. Enter the alias public IP for the eth1 interface. When the failover occurs, the standby server will automatically clone the cluster public IP on the designated network interface, probably eth1.
  2. Determine whether the standby local IP address HA-OSCAR has selected is occupied. If this IP address is in use, please select a new one. Otherwise, keep this default.
  3. Leave the last two items unchanged.
  4. Click Add Standby Server.

Standby Server initial network configuration
Figure 5. Standby server initial network configuration

This step will take less than a minute. When the successful status window pops up, click on the Close button.

Retrieve Standby Server MAC Address (For PXE Boot) and Build the Image on its Local Drive

Pay close attention to the following procedures to retrieve the standby server's MAC address for PXE booting before building its images on the local drive. One of the standby server network interfaces, typically eth0, connects to the private LAN and broadcasts its MAC address during its network boot.

Whenever the primary server is ready to build the standby server image, it starts cloning its images with the collected addresses. Consequently, the standby server will fetch the image by network booting the standby server via PXE (or floppy) from the primary server or an optional image server on its local file system. When the cloning succeeds, the server will reboot from its hard disk. This marks the completion of the standby server installation.

To assign the standby server's MAC address and build a local image on the standby server, proceed to step 4 in "Network Setup & Make boot server." HA-OSCAR will display the standby server MAC address configuration screen as shown in Figure 6.

Standby Server MAC address configuration
Figure 6. Standby server MAC address configuration

Step 4 contains the following procedures:

  1. Click on the Setup Network Boot button.
  2. Click on the Start Collect MAC address button to instruct the primary server to collect the standby server's MAC address.
  3. Switch to the standby server terminal, configure its boot sequence to start with the network boot, and reboot the standby system. Make sure the standby server eth0 is connected to the local switch where the primary server PXE daemon will listen to the broadcast boot request. Otherwise, the primary server will not be able to collect the standby MAC address in the next step.
  4. Toggle back to the primary server screen; it should now show the standby server's MAC address (Figure 7).
  5. Assign the MAC address to the standby server network interface (e.g. eth0).
  6. Click on Configure DHCP Server.
  7. Toggle back to the standby server terminal and reboot it; you're now ready to build a local image on the standby server. This step takes 30 minutes to one hour, so please be patient.
  8. When the standby server image completes, make sure to set the server boot device as its local hard disk. Reboot the system.

Standby Server MAC address collection
Figure 7. Standby server MAC address configuration after MAC address collection

Completing the HA-OSCAR Installation

Having completed all four steps, the cluster should have all of its packages installed. The cluster should be ready to use or test. HA-OSCAR also provides a web-based management to customize the HA-OSCAR configuration, including the capability to enable new outage monitor/detection modules and failover capabilities. However, this is a feature for advanced users only, as it may cause invalid cluster configurations if you incorrectly configure HA-OSCAR parameters. The next section elaborates on this topic.

HA-OSCAR Monitoring and Configuration Webmin (Optional)

HA-OSCAR provides a default self-healing system resource and outage monitoring health and recovery mechanism. It also provides a web-based service monitoring and configuration program based on WebMin and Mon. You can use HA-OSCAR Webmin to customize resource managing, configuring, and service monitoring.

The following sections describe step by step how to manually configure the virtual network interface, (heartbeat) detection channel, and optional service monitoring configurations. Again, we intended to support the following procedures and features only for advanced users. The normal initial head node configuration steps are:

  • Set up detection channels and configurations on the primary server.
  • Set up detection channels and configurations on the standby server.
  • Enable the optional HA-OSCAR service monitoring (only for advanced users).

Primary Server Setup

Access HA-OSCAR Webmin by opening http://localhost:10000 (but only if you have it running) and selecting the HA-OSCAR category to configure the system (Figure 8). A manual configuration (Figure 9) involves the following steps:

  1. Add a virtual network interface to eth0 and eth1.
  2. Define channel detection: a public network and its virtual interface (virtual public IP, which is the same public IP for both primary and standby severs) and a private network and its virtual interface. This is for IP cloning and channel detection.

Other users also can later log in and manage your system with the web-based tool.

setting up a virtual network interface and
detection channel
Figure 8. Step-by-step instructions to set up a virtual network interface and detection channel

the main Webmin screen
Figure 9. The main Webmin screen

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