Chapter 2. Removing And Replacing Parts; Enabling Concurrent Maintenance - IBM SAN Volume Controller 2145-CG8 Hardware Maintenance Manual

Chapter 2. Removing and replacing parts

You can remove and replace field-replaceable units (FRUs) from the SAN Volume Controller, redundant
ac-power switch, and uninterruptible power supply.
Each FRU has its own removal procedure. Sometimes you can find that a step within a procedure might
refer you to a different remove/replace procedure. You might want to complete the new procedure before
you continue with the first procedure that you started.
Remove or replace parts only when you are directed to do so by the IBM System Storage SAN Volume
Controller Troubleshooting Guide. Start all problem determination and repair procedures with MAP 5000.

Enabling concurrent maintenance

To allow concurrent maintenance, SAN Volume Controllers must be configured in pairs.
While one SAN Volume Controller is being serviced, the other keeps the I/O group operational. With
concurrent maintenance, all field-replaceable units (FRUs) can be removed, replaced, and tested on one
SAN Volume Controller while the SAN and host systems are powered on and doing productive work.
Attention: Do not remove the power from both SAN Volume Controllers unless the procedures instruct
you to do so.
Perform the following checks to verify that concurrent maintenance is enabled.
It is particularly important to perform these checks if a node contains solid-state drives (SSDs) because
volumes on the SSDs might not be mirrored.
1. Confirm that no hosts have dependencies on the node.
When shutting down a node that is part of a system or when deleting the node from a system, you
can use either the management GUI or a command-line interface (CLI) command. In the management
GUI, click System Status. Click the correct node and click Manage to display all the volumes that are
dependent on a node. You can also use the node parameter with the lsdependentvdisks CLI command
to view dependent volumes.
If dependent volumes exist, determine if the volumes are being used. If the volumes are being used,
either restore the redundant configuration or suspend the host application. If a dependent quorum
disk is reported, repair the access to the quorum disk or modify the quorum disk configuration.
2. Ensure that the host multipathing device drivers can fail over to the partner node.
Some host multipathing device drivers take a while to update after changes are made on the fabric.
Do not shut down a node or delete the node from a cluster if the partner node in the I/O group to
which the node belongs has not been online for more than 30 minutes.
If possible, check the status of the host multipathing device drivers before shutting down a node to
ensure that the device drivers can fail over to the partner node.
When shutting down the node, see MAP 5350 in the IBM System Storage SAN Volume Controller
Troubleshooting Guide for a description of how to check for dependencies on the node during the
procedure to turn off the node.
When deleting a node from the cluster, see "Deleting a node from a cluster using the management GUI"
in the IBM System Storage SAN Volume Controller Troubleshooting Guide for a description of node
© Copyright IBM Corp. 2003, 2011
25