IBM System storage DS6000 Series, Attachment Manual

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If a system has storage unit devices attached but the storage unit device specific
object data manager (ODM) is not installed, the storage unit is configured as other
FC disk . When you upgrade the system to AIX 5L Version 5.2 with the 5200-01 with
the Recommended Maintenance package, the storage unit is no longer configured
as other FC disk . These devices are configured as MPIO other FC disk . A device
is only configured as MPIO other FC disk if the device is MPIO-capable and no
device-specific ODM is installed.
The following sections outline the differences between the
other FC disk
and
MPIO
other FC disk
configurations. A path is each physical connection between the host
system and the device. A path control module is a device-specific module that
manages device I/O across its paths.
A device configured as other FC disk has the following properties:
v
It contains multiple device instances that are created for each path where the
device was detected.
v It supports user-changeable device attributes.
v It can migrate to a vendor-specific device when vendor-supplied, device-specific
ODM predefines are installed.
v
It is meant to be in a transitory state during boot and install. Always install the
vendor-specific device ODM predefines before using the device in a production
environment.
A device configured as MPIO other FC disk has the following properties:
v
It contains only one device instance and multiple path instances. It also contains
one path instance for each physical connection between the host system and the
device.
v
It supports user-changeable device attributes. There might be additional
attributes that are specific to a path control module.
v It can migrate to a vendor-specific device when you install vendor-supplied
device-specific ODM predefines.
v It presently is not supported by SDD path-management products. To support
SDD path management, you must install the vendor-specific non-MPIO ODM
predefines. Your attempt to control a device that is configured as an MPIO device
with SDD can produce undetermined results. Data integrity issues can exist if
you operate the device in this configuration.
v It is supported in a production environment. Device-specific vendor ODM
predefines are not required to be installed before you use the device in a
production environment. A device-specific MPIO-capable ODM is available for the
storage unit.
v It allows you to install and boot to an MPIO device.
If a system has storage unit devices attached and the storage unit device-specific
ODM is installed, the storage unit is configured as storage unit-XXX disks. When
the system is upgraded to AIX 5L version 5.2 with the 5200-01 Recommended
Maintenance package, the storage unit does migrate the MPIO other FC disk
configuration. The
MPIO other FC disk
configuration is only used for devices that
support AIX MPIO and do not have device-specific ODM installed.
MPIO-capable and non-MPIO versions of the storage unit ODM are available. The
non-MPIO version is compatible with current releases of SDD. The MPIO-capable
version of the storage unit ODM is not compatible with current releases of SDD. For
Chapter 9. Attaching to an IBM RS/6000 or IBM eServer pSeries host
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