Users Guide

failover or High Availability (HA) functionality. The expander splits the internal drive array between the two storage 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:
• Unied 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 rst 12 drives and the second controller has access to the last 12 drives. The
drives connected to the rst 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 rst 4 drives and the second controller has access to the last 20 drives. The
drives connected to the rst 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 rst 8 drives and the second controller has access to the last 16 drives. The
drives connected to the rst 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 rst 16 drives and the second controller has access to the last 8 drives. The
drives connected to the rst 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 rst 20 drives and the second controller has access to the last 4 drives. The
drives connected to the rst controller are numbered 0-19 while the drives connected to the second controller are numbered
20-23.
• Information Not Available — Controller information is not available.
iDRAC allows the split mode setting if the expander has the capability to support the conguration. 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
congured and does not check whether the second PERC controller is present.
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 conguration multiple times.
• The backplane splitting operation can cause data loss or foreign conguration if the drive association changes from one
controller to another controller.
• During the backplane splitting operation, the RAID conguration may be impacted depending on the drive association.
Any change in this setting only takes eect after a system power reset. If you change from Split mode to Unied, an error message
is displayed on the next boot as the second controller does not see any drives. Also, the rst controller will see a foreign
conguration. If you ignore the error, the existing virtual disks are lost.
Conguring backplane mode using web interface
To congure backplane mode using iDRAC web interface:
1. In the iDRAC web interface, go to Overview → Storage → Enclosures → Setup
The Enclosure Setup page is displayed.
2. From the Controller drop-down menu, select the controller to congure its associated enclosures.
3. In the Value column, select the required mode for the required backplane or enclosure:
• Unied Mode
• Split Mode
215