Upgrading To Dual-Controller Configuration - Dell EMC ME4 Series Owner's Manual

• 2U (rack space) controller enclosure (2U24)– see
system—rear orientation
• 5U (rack space) controller enclosure (5U84)– see
system—rear orientation: holds up to 84 low profile (1-inch high) 3.5" form factor disk drive modules in a vertical orientation within the
disk drawer. Two vertically-stacked drawers each hold 42 disks. If used, 2.5" disks require 3.5" adapters. These same chassis form
factors are used for supported expansion enclosures.
These same chassis form factors are used for supported expansion enclosures; albeit with different I/O modules (IOMs). Each redundant
CRU module is hot pluggable and replaceable on site. Whereas the 2U12 and 2U24 enclosures support single or dual-IOM configuration, the
5U84 enclosure supports dual-IOM configuration exclusively. If a partner controller fails, the storage system will fail over and run on a single
controller until the redundancy is restored. For 5U84 enclosures, an IOM must be installed in each IOM slot. For 2U enclosures, an IOM
must be installed in IOM slot A, and either an IOM or IOM-blank must be installed in IOM-slot B to ensure sufficient airflow through the
enclosure during operation.
NOTE: Throughout this guide—and the management interfaces documents used with this guide—I/O module (IOM) is a general
term denoting either a controller module or an expansion module.

Upgrading to dual-controller configuration

You can upgrade a 2U ME4 single-controller configuration by adding a second controller in Slot B.
Controller B can be added while Controller A continues to process Host I/O requirements. However, we recommend scheduling
configuration changes during a maintenance window with low or no I/O activity.
Data is not impacted when a second Controller B is inserted into the live array, but we recommended doing a complete data backup before
proceeding.
NOTE:
• When a second controller is inserted, the redundancy setting is automatically revised from Single Controller to Active-
Active ULP (Unified LUN Presentation). No manual changes are necessary.
• If PFU (partner firmware upgrade) is enabled, when you add a second controller, the system automatically updates the firmware on
Controller B to match the firmware version on Controller A.
1 Confirm that array redundancy is configured as Single Controller Mode by entering the #show advanced-settings CLI
command.
This step will ensure that Controller A does not report Controller B as missing.
2 Remove the blank IOM from Slot B.
3 Grasp the IOM using both hands, and with the latch in the open position, orient the module and align it for insertion into the target
IOM slot.
4 Ensuring that the IOM is level, slide it into the enclosure as far as it will go.
A controller module that is only partially seated will prevent optimal performance of the controller enclosure. Verify that the controller
module is fully seated before continuing.
5 Set the module in position by manually closing the latch.
You should hear a click as the latch handle engages and secures the IOM to its connector on the back of the midplane.
6 Connect the cables.
7 Map the host ports on Controller B.
Removing a second controller
To remove a second controller and revert back to a single-controller configuration:
1 Shut down Controller B.
2 Remove the controller from the array.
Figure 3. 2U24 enclosure system—front orientation
: holds up to 24 low profile (5/8 inch high) 2.5" form factor disk drive modules in a vertical orientation.
Figure 5. 5U84 enclosure system—front orientation
and Figure 4. 2U24 enclosure
and Figure 6. 5U84 enclosure
Storage system hardware 7