HP-UX 11i v3 Crash Dump Improvements

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chosen, with the following exception: concurrent HBAs will always be selected over reentrant

HBAs once the available ports have all been used. This exception is due to the fact that having

more than one reentrant device on the same HBA port will not increase parallelism.

Offline or disabled paths are not included in the automatic HBA selection. See Section 5,

”Availability and Manageability Improvements”, for information regarding automatic

reconfiguration across path offline events.

Figure 10 illustrates how this would work in an example configuration. In this example there are

6 dump devices and 4 HBA ports, each of which has paths to all 6 of the devices. Three of the

HBA ports are reentrant, and one is concurrent. The first 4 dump devices configured will each be

assigned a path to a different HBA port. The 5

and 6

devices will be assigned paths through

the concurrent HBA, resulting in the 6 dump units shown below.

Figures 11 and 12 illustrate the impact that configuration ordering can have on path selection in

some configurations. In this example there are two devices and two HBA ports. The HBA port

named hba1 has paths to both devices, while hba2 only has a path to Dev2. If, as shown in

Figure 11, Dev2 is configured first and hba1’s path is selected then when Dev1 is configured it

would also be configured through hba1 (its only path). The red lines in Figure 11 indicate the

configured dump paths, which go through hba1 for both devices. To maximize parallelism the two

devices should be configured on separate HBA ports.

The system administrator can deal with such situations by careful ordering of dump device

configurations (configuring Dev1 before Dev2) or by disabling of lun paths

(i.e., disabling the

path from hba1 to Dev2 in this case) to better balance the dump configuration across the available

In the example in Figure 11 only one dump unit would be created if the HBAs were reentrant. If the HBAs were concurrent then two dump

units would be created regardless of the configuration order. However, even in the concurrent case it is recommended that the devices be

spread across the available HBAs to maximize performance.

= available CPUs = CPUs used during dump

= dump device

labeled

Dev1

through

Dev6

representing the order they were configured

= reentrant HBA port

Uncompressed Dump

(6 dump units, 6 HBA ports)

Figure 10 – Automatic HBA Selection

Dev1

Dev3

Dev2

Dev4

Dev5

Dev6

= concurrent HBA port