User Manual

Troubleshooting
6-12
Controller on page 5-21). The controllers will stop boot-up to show
messages on the LCD. The messages and corresponding resolutions are
the same as failure of replacement controller.
If the two controllers have different versions of boot code or firmware, you
need to choose between the versions. If the two controllers have different
BBM option, you need to choose to enable or disable it. If ENC SN UNEQ is
displayed, the two controllers came from different chassis, and you need
to boot up first with only one controller as the master controller, and install
the other controller later.
3. Host computer reports I/O errors during path/
controller failover
If you use MPIO against path or controller failure, it is essential to check if
your MPIO driver is installed properly. Below are the checking items you
need to do:
• A virtual disk has been mapped to LUNs of all host-interface ports in
simple storage presentation configuration. Or, a virtual disk has been
mapped to a host or host group in symmetric storage presentation
configuration.
• Because a LUN is not accessible during regular initialization. Install the
MPIO driver after the regular initialization of a virtual disk is done, or
use background initialization.
• All cables are connected and the corresponding paths are
displayed by the MPIO software utility.
• Check the device nodes from the operating system disk
management utility to make sure the MPIO devices have been
created. Make sure the number of MPIO devices matches your
cabling topology (see 5.1 Multi-Path IO Solutions on page 5-1 for
how to calculate the number).
4. The replacement controller cannot work for controller fail
back
The replacement controller stops boot-up if it fails to discover the same
set of expansion chassis of the surviving controller. You need to make sure
the expansion chassis are properly attached to the expansion port of the
replacement controller and there is no broken connection between the
expansion chassis. Please also note that the I/O access and background
tasks can be migrated to the replacement controller only after the host-
interfaces of the replacement controller are properly connected to the
host computers.