Interface Card Critical Resource Analysis(CRA) Whitepaper for HP-UX 11i v3

DLKM Driver unload scenarios
Scenario 21
System Configuration:
A logical volume (could be either LVM or VxVM volume) has been created with
two or more disks (that is, PVs), each PV has a single lunpath through same or different cards and a
file system is residing on that logical volume.
Operation Performed: # kcmodule <interface driver associated with card>=unused
Criticality reported by CRA:
CRA_DATA_CRITICAL
Explanation and user action required:
The above kcmodule operation on any of the I/O drivers controlling a card, which provides a lunpath
to the PV, will fail with CRA_DATA_CRITICAL error.
If this operation must be performed for system administration purposes, then an alternative path must
be configured using different I/O driver than the one that is about to be unloaded, before performing
the above operation.
Scenario 22
System Configuration:
HP-UX OS is running and a card in one of the I/O slots is connected to some
critical resources, such as boot disk, disk with a File system, SG quorum disk, etc. The driver
associated with the card is a Dynamically Loadable Kernel Module (DLKM) driver.
Operation Performed:
User tries to remove the driver software of the dynamically loaded kernel I/O
driver associated with the card, using the SD-UX swremove command.
Criticality reported by CRA:
The CRA result is not reported to the user.
Explanation and user action required:
In such a scenario, where the dynamically loaded kernel I/O driver is in use, removing the driver
software using the swremove command will need a system reboot to complete operation. The
recommended procedure to avoid this system reboot is to perform CRA analysis using the kcmodule
unload operation first before removing the driver software.
If the CRA reports any critical resource usage, configure another alternative path to the resource using
a different dynamically loadable I/O driver, then unload the I/O driver, for which the associated
software must be removed from the system. Thereafter, proceed to remove the driver software.
If the system has an earlier version of the I/O driver, which is statically linked, then regardless of
criticality of the driver usage the swremove operation will result in system reboot.
However, if the earlier version of the I/O driver is also a dynamically loadable kernel module, then
the swremove operation will result in system reboot only if the concerned I/O driver has any critical
resource usage.
If there is no critical usage of the I/O driver, the swremove will not result in system reboot.
16