Dell EMC ME4 Series - Upgrading to dual-controller configuration

• 2U (rack space) controller enclosure (2U24)– see Figure 3. 2U24 enclosure system—front orientation and Figure 4. 2U24 enclosure
system—rear orientation : holds up to 24 low prole (5/8 inch high) 2.5" form factor disk drive modules in a vertical orientation.
• 5U (rack space) controller enclosure (5U84)– see Figure 5. 5U84 enclosure system—front orientation and Figure 6. 5U84 enclosure
system—rear orientation: holds up to 84 low prole (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 dierent 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 conguration, the
5U84 enclosure supports dual-IOM conguration 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 sucient airow 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 conguration
You can upgrade a 2U ME4 single-controller conguration 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
conguration 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 (Unied LUN Presentation). No manual changes are necessary.
• If PFU (partner rmware upgrade) is enabled, when you add a second controller, the system automatically updates the rmware on
Controller B to match the rmware version on Controller A.
1
Conrm that array redundancy is congured 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 conguration:
1 Shut down Controller B.
2 Remove the controller from the array.
Storage system hardware
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