84 Troubleshooting
To rescan using RAIDar (v2):
1. Verify that both controllers are operating normally.
2. In the Configuration View panel, right-click the system and select Tools > Rescan Disk Channels.
3. Click Rescan.
NOTE: The reordering enclosure IDs action only applies to Dual Controller mode. If only one controller is
available, due to either Single Controller configuration or controller failure, a manual rescan will not
reorder the drive enclosure IDs.
Stopping I/O
When troubleshooting disk drive and connectivity faults, stop I/O to the affected disk groups from all hosts
and remote systems as a data protection precaution. As an additional data protection precaution, it is
helpful to conduct regularly scheduled backups of your data.
IMPORTANT: Stopping I/O to a disk group is a host-side task, and falls outside the scope of this
document.
When on-site, you can verify that there is no I/O activity by briefly monitoring the system LEDs; however,
when accessing the storage system remotely, this is not possible. Remotely, you can use the show
disk-group-statistics command to determine if input and output has stopped. Perform these steps:
1. Using the CLI, run the show disk-group-statistics command.
The Reads and Writes outputs show the number of these operations that have occurred since the
statistic was last reset, or since the controller was restarted. Record the numbers displayed.
2. Run the show disk-group-statistics
command a second time.
This provides you a specific window of time (the interval between requesting the statistics) to determine
if data is being written to or read from the disk group. Record the numbers displayed.
3. To determine if any reads or writes occur during this interval, subtract the set of numbers you recorded
in step 1 from the numbers you recorded in step 2.
• If the resulting difference is zero, then I/O has stopped.
• If the resulting difference is not zero, a host is still reading from or writing to this disk group.
Continue to stop I/O from hosts, and repeat step 1 and step 2 until the difference in step 3 is zero.
NOTE: See the CLI Reference Guide for additional information.
Diagnostic steps
This section describes possible reasons and actions to take when an LED indicates a fault condition during
initial system setup. See Appendix A – LED descriptions for descriptions of all LED statuses.
NOTE: Once event notification is configured and enabled using either the SMC or RAIDar, you can view
event logs to monitor the health of the system and its components using the GUI.
In addition to monitoring LEDs via line-of-sight observation of the racked hardware components when
performing diagnostic steps, you can also monitor the health of the system and its components using the
management interfaces previously discussed. Bear this in mind when reviewing the Actions column in the
following diagnostics tables, and when reviewing the step procedures provided later in this chapter.
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