HP A6829A PCI Dual Channel Ultra160 SCSI Host Bus Adapter Service and User Guide (May 2003)

Installing the A6829A Adapter
Installing the A6829A Adapter
Chapter 218
During an adapter replacement operation, SAM performs a Critical
Resource Analysis (CRA), which checks all channels on the target
adapter for critical resources that will be temporarily unavailable while
the adapter is shut down.
Planning and Preparation
As mentioned earlier, for the most part, SAM prevents you from
performing OLAR procedures that would adversly affect other areas of
the HP-UX system. See Configuring HP-UX For Peripherals for detailed
information.
Critical Resources
Replacing an adapter that is still operating can have adverse
consequences. As power to the slot must be off when the old adapter is
removed and the new adapter is inserted, you must consider the effects
of shutting down the adapter’s functions.
This is particularly important if no online failover or backup adapter to
pick up those functions is installed. For example:
• Which mass storage devices will be temporarily disconnected when
the adapter is shut down?
• Will a critical networking connection be lost?
A critical resource is one that would cause a system crash or prevent the
operation from completing successfully if the resources were temporarily
suspended or disconnected. For example, if the SCSI adapter to be
replaced connects to the unmirrored root disk or swap space, the system
will crash when the adapter is shut down.
During an OLAR procedure, it is essential to check the targeted adapter
for critical resources, as well as the effects of existing disk mirrors and
other situations where an adapter’s functions can be taken over by
another adapter that will not be affected.
As mentioned earlier, SAM performs a thorough CRA automatically, and
presents options based on its findings. If you determine that critical
resources will be affected by the procedure, you could replace the adapter
when the system is offline. On the other hand, if you are required to take
an action immediately, you can use the rad command to try an online
addition of a backup adapter and deletion of the target adapter.