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Creating a Communication Path

Before configuring a LifeKeeper communication path between servers, verify the hardware and software setup. For more information, see the SPS for Linux Release Notes

To create a communication path between a pair of servers, you must define the path individually on both servers. LifeKeeper allows you to create both TCP (TCP/IP) and TTY communication paths between a pair of servers. Only one TTY path can be created between a given pair. However, you can create multiple TCP communication paths between a pair of servers by specifying the local and remote addresses that are to be the end-points of the path. A priority value is used to tell LifeKeeper the order in which TCP paths to a given remote server should be used.

IMPORTANT: Using a single communication path can potentially compromise the ability of servers in a cluster to communicate with one another. If a single comm path is used and the comm path fails, LifeKeeper hierarchies may come in service on multiple servers simultaneously. This is known as "false failover". Additionally, heavy network traffic on a TCP comm path can result in unexpected behavior, including false failovers and LifeKeeper initialization problems.

  1. There are four ways to begin.

  2. A dialog entitled Create Comm Path will appear. For each of the options that follow, click Help for an explanation of each choice.

  3. Select the Local Server from the list box and click Next.

  4. Select one or more Remote Servers in the list box. If a remote server is not listed in the list box (i.e. it is not yet connected to the cluster), you may enter it using Add. You must make sure that the network addresses for both the local and remote servers are resolvable (for example, with DNS or added to the /etc/hosts file). Click Next.

  5. Select either TCP or TTY for Device Type and click Next.

  6. Select one or more Local IP Addresses if the Device Type was set for TCP. Select the Local TTY Device if the Device Type was set to TTY. Click Next.

  7. Select the Remote IP Address if the Device Type was set for TCP. Select the Remote TTY Device if the Device Type was set to TTY. Click Next.

  8. Enter or select the Priority for this comm path if the Device Type was set for TCP. Enter or select the Baud Rate for this Comm Path if the Device Type was set to TTY. Click Next.

  9. Click Create. A message should be displayed indicating the network connection is successfully created. Click Next.

  10. If you selected multiple Local IP Addresses or multiple Remote Servers and the Device Type was set for TCP, then you will be taken back to Step 6 to continue with the next Comm Path. If you selected multiple Remote Servers and the Device Type was set for TTY, then you will be taken back to Step 5 to continue with the next Comm Path.

  11. Click Done when presented with the concluding message.

You can verify the comm path by viewing the Server Properties Dialog or by entering the command lcdstatus -q. See the LCD(1M) man page for information on usinglcdstatus. You should see an ALIVE status.

In addition, check the server icon in the right pane of the GUI. If this is the first comm path that has been created, the server icon shows a yellow heartbeat, indicating that one comm path is ALIVE, but there is no redundant comm path. server_status_nodewarning.gif

The server icon will display a green heartbeat when there are at least two comm paths ALIVE. server_status_active.gif

IMPORTANT: When using IPv6 addresses to create a comm path, statically assigned addresses should be used instead of auto-configured/stateless addresses as the latter may change over time which will cause the comm path to fail.

If the comm path does not activate after a few minutes, verify that the paired server's computer name is correct. If using TTY comm paths, verify that the cable connection between the two servers is correct and is not loose. Use the portio(1M) command if necessary to verify the operation of the TTY connection.

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