Recently a Continuent Customer Asked: Part 6 — Why Do I Get the Dreaded “NOT A MEMBER” Error When Running the tpm Command?

Summary

In this blog, part 6 of a series of “Recently a Customer Asked” posts for Tungsten University, we explore the reason for the dreaded "NOT A MEMBER" error when running the `tpm` command and possible root causes, along with steps to fix.

The Question

"What is the meaning of the `NOT A MEMBER` error when running the `tpm diag` command?”

shell> tpm diag
...
WARN: >>> tpm_diag - host db1 is NOT A MEMBER

The Answer

This happens because the nodename defined in the Tungsten configuration does not match exactly with the output from the OS `hostname` command.

The root cause of the `NOT A MEMBER` error is often because the OS hostname defined in the `/etc/sysconfig/network` or `/etc/hostname` files is using the short hostname, but the `/etc/tungsten/tungsten.ini` file is using the long, Fully Qualified Domain Name (FQDN) hostname.

As of v7.0.2, the `tpm diag` command works when the nodename defined in the tungsten.ini file is the shortname, and DNS or /etc/hosts returns the FQDN. Before that, the same error would occur.

There is no way to create a code-based fix for the situation where the Tungsten value is the FQDN and the `hostname` command outputs the short hostname because there is the possibility for multiple matches in the Tungsten configuration and no way to differentiate properly.

So, the two solutions are:

1. Edit `/etc/sysconfig/network` (or `/etc/hostname` depending on your linux flavor) and set the HOSTNAME={$FQDN}, then reboot the node while shunned.
2. In maintenance mode, edit `/etc/tungsten/tungsten.ini` on all nodes to use the short hostname, then run `tpm update` on every node including connectors. This will cause an outage because the connectors will restart.

Best Practice

The best practice is to ensure that the output of the `hostname` command and the nodename entries in the Tungsten configuration match exactly prior to installing Tungsten.

When creating a configuration, use the output of the `hostname` command to populate the nodename entries - the values inside the INI must match the hostname output, so if you are using short hostnames, then use the short name inside the INI, and if your hostname command returns the FQDN, then use the FQDN in the INI file.

The configuration keys that define node names in the Tungsten configuration are:

• --slaves
• --dataservice-slaves
• --members
• --master
• --dataservice-master-host
• --masters
• --relay

In every option listed above, ensure the entries match the `hostname` command exactly.

Wrap-Up

In this blog, part 6 of a series of “Recently a Customer Asked” posts for Tungsten University, we examined the reason for the dreaded "NOT A MEMBER" error when running the `tpm` command and possible root causes, along with steps to fix.

Smooth sailing!