Deployment Guide

Correcting enclosure IDs
When installing a system with expansion enclosures attached, the enclosure IDs might not agree with the physical cabling order. This issue
occurs if the controller was previously attached to enclosures in a different configuration, and the controller attempts to preserve the
previous enclosure IDs.
To correct this condition, ensure that both controllers are up, and perform a rescan using the PowerVault Manager or the CLI. The rescan
reorders the enclosures, but it can take up to two minutes to correct the enclosure IDs.
NOTE: Reordering expansion enclosure IDs only applies to dual-controller mode. If only one controller is available, due to
a controller failure, a manual rescan does not reorder the expansion enclosure IDs.
• To perform a rescan using the PowerVault Manager:
1. Verify that both controllers are operating normally.
2. In the System tab, click Action, and select Rescan Disk Channels.
• To perform a rescan using the CLI, type the following command:
rescan
Host I/O
When troubleshooting disk drive and connectivity faults, stop I/O to the affected disk groups from all hosts as a data protection
precaution.
As an extra data protection precaution, it is helpful to conduct regularly scheduled backups of your data. See “Stopping I/O” in the Dell
EMC PowerVault ME4 Series Storage System Owner’s Manual.
Dealing with hardware faults
Make sure that you have a replacement module of the same type before removing any faulty module. See “Module removal and
replacement” in the Dell EMC PowerVault ME4 Series Storage System Owner’s Manual.
NOTE:
If the enclosure system is powered up and you remove any module, replace it immediately. If the system is used
with any modules missing for more than a few seconds, the enclosures can overheat, causing power failure and potential
data loss. Such action can invalidate the product warranty.
NOTE: Observe applicable/conventional ESD precautions when handling modules and components, as described in
Electrical safety on page 8. Avoid contact with midplane components, module connectors, leads, pins, and exposed
circuitry.
Isolating a host-side connection fault
During normal operation, when a controller module host port is connected to a data host, the port host link status/link activity LED is
green. If there is I/O activity, the host activity LED blinks green. If data hosts are having trouble accessing the storage system, but you
cannot locate a specific fault or access the event logs, use the following procedures. These procedures require scheduled downtime.
NOTE:
Do not perform more than one step at a time. Changing more than one variable at a time can complicate the
troubleshooting process.
Host-side connection troubleshooting featuring CNC ports
The following procedure applies to controller enclosures with small form factor pluggable (SFP+) transceiver connectors in 8/16 Gb/s FC
or 10 GbE iSCSI host interface ports.
In this procedure, SFP+ transceiver and host cable is used to refer to any qualified SFP+ transceiver supporting CNC ports
used for I/O or replication.
NOTE:
When experiencing difficulty diagnosing performance problems, consider swapping out one SFP+ transceiver at
a time to see if performance improves.
1. Stop all I/O to the storage system. See “Stopping I/O” in the Dell EMC PowerVault ME4 Series Storage System Owner’s Manual.
2. Check the host link status/link activity LED.
If there is activity, stop all applications that access the storage system.
3. Check the Cache Status LED to verify that the controller cached data is flushed to the disk drives.
Troubleshooting and problem solving
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