Users Guide

Table Of Contents
controllers. In this mode, virtual disk creation only displays the drives connected to a particular controller. There are no licensing
requirements for this feature. This feature is supported only on a few systems.
Backplane supports the following modes:
Unified mode This is the default mode. The primary PERC controller has access to all the drives connected to the
backplane even if a second PERC controller is installed.
Split mode One controller has access to the first 12 drives and the second controller has access to the last 12 drives. The
drives connected to the first controller are numbered 0-11 while the drives connected to the second controller are numbered
12-23.
Split mode 4:20 One controller has access to the first 4 drives and the second controller has access to the last 20
drives. The drives connected to the first controller are numbered 0-3 while the drives connected to the second controller are
numbered 4-23.
Split mode 8:16 One controller has access to the first 8 drives and the second controller has access to the last 16
drives. The drives connected to the first controller are numbered 0-7 while the drives connected to the second controller are
numbered 8-23.
Split mode 16:8 One controller has access to the first 16 drives and the second controller has access to the last 8 drives.
The drives connected to the first controller are numbered 0-15 while the drives connected to the second controller are
numbered 16-23.
Split mode 20:4 One controller has access to the first 20 drives and the second controller has access to the last 4 drives.
The drives connected to the first controller are numbered 0-19 while the drives connected to the second controller are
numbered 20-23.
Split mode 6:6:6:6 4 blades installed in one chassis and each blade have 6 drives assigned. This mode is only supported on
PowerEdge C series blades.
Information Not Available Controller information is not available.
iDRAC allows the split mode setting if the expander has the capability to support the configuration. Ensure that you enable this
mode prior to installing the second controller. iDRAC performs a check for expander capability prior to allowing this mode to be
configured and does not check whether the second PERC controller is present.
NOTE:
Cable errors (or other errors) may appear if you put the backplane into split mode with only one PERC attached, or
if you put the backplane into Unified Mode with two PERCs attached.
To modify the setting, you must have Server Control privilege.
If any other RAID operations are in pending state or any RAID job is scheduled, you cannot change the backplane mode.
Similarly, if this setting is pending, you cannot schedule other RAID jobs.
NOTE:
Warning messages are displayed when the setting is being changed as there is a possibility of data loss.
LC Wipe or iDRAC reset operations do not change the expander setting for this mode.
This operation is supported only in real-time and not staged.
You can change the backplane configuration multiple times.
The backplane splitting operation can cause data loss or foreign configuration if the drive association changes from one
controller to another controller.
During the backplane splitting operation, the RAID configuration may be impacted depending on the drive association.
Any change in this setting only takes effect after a system power reset. If you change from Split mode to Unified, an error
message is displayed on the next boot as the second controller does not see any drives. Also, the first controller will see a
foreign configuration. If you ignore the error, the existing virtual disks are lost.
Configuring backplane mode using web interface
To configure backplane mode using iDRAC web interface:
1. In the iDRAC web interface, go to Configuration > Storage Configuration > Enclosures Configuration.
2. From the Controller menu, select the controller to configure its associated enclosures.
3. From the Action drop-down menu, select Edit Enclosure Mode.
The Edit Enclosure Mode page is displayed.
4. In the Current Value column, select the required enclosure mode for the backplane or enclosure. The options are:
Unified Mode
Split Mode
Split Mode 4:20
Managing storage devices
263