- Add power distribution units

# Add power distribution units

Contents

This section configures power distribution units (PDUs) and assigns PDU outlets to servers to support high availability (HA).

Note: A server cannot be associated with both a BMC and PDU outlets. Use PDUs or IPMI/BMCs to support failover.

Note: This section is for configuring managed storage servers, as previously set up in Add storage servers. You should configure PDUs based on primary and failover server configuration, per volume. This section (Add power distribution units) does not apply to servers that are monitor-only.

## Issues Regarding Power Loss to the BMC or PDU

Regarding failover, if the method of power control is not functioning (e.g., loss of power to the fencing device, misconfiguration, etc.), then HA will be unable to fail the targets from the failed server to its failover server. This is because in order to complete failover, the failover server needs to be able to guarantee that the failed server can no longer access targets running on it. The only way to be sure of this is to power-down the failed server. Thus, the failover server needs to be able to communicate with the fencing device of the failed server for failover to occur successfully.

With IPMI, the power for each HA server and its fencing device is coupled together. This means there are more scenarios where both may lose power at once (chassis power failure, motherboard failure, etc.). In such a case, if a server suffers chassis power failure such that the BMC is no longer able to operate, HA will be unable to fail the targets over. To remedy this situation, restore power to the chassis of the failed server to restore the functionality of your file system. If HA coverage for the scenarios just described is important to you, we strongly recommend using smart PDUs, rather than IPMI as your fencing device.

For a PDU, power loss to the PDU will mean that HA will be unable to fail the targets over. As in the above situation, the remedy is to restore power to the PDU to restore the functionality of your file system. We recommend redundant PDUs if availability is critical. This approach is a necessary limit of HA to protect the integrity of the targets being failed over.

At the PDUs window you can add PDUs and then assign specific PDU outlets to specific servers. You should have at least two PDUs to support failover.

To add PDUs:

1. | At the menu bar, click the Configuration drop-down menu and click Power Control.

2. | With no power distribution units recognized, this window will read: No power distribution units are configured. Click + Add PDU.

3. | At the Add PDU dialogue window, select the PDU device type from the drop-down list.

4. | Enter a name for this PDU. (If not entered, this field will default to the IP address.)

5. | Enter the IP address for the PDU. If not known, enter a DNS-resolvable hostname. The address is stored as an IPv4 address. Note: This address is always stored as an IPv4 address, so if the mapping from hostname to IPv4 address later changes in DNS, it will need to be updated here as well.

6. | Enter the port number. This port number must be unique to this PDU.

7. | Enter your Management user name.

8. | Enter your Management password. Then click Save.

Proceed to Assign PDU outlets to servers.