HP-UX 11i v3 Crash Dump Improvements
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HBA ports. This situation is illustrated in Figure 12, in which reordering or disabling produces a
dump configuration in which both HBA ports are used.
Note: The results in Figure 12 can be accomplished by disabling the lun path after the dump
configuration is complete, without worrying about ordering or disabling until then. This will cause
auto-reconfiguration and selection of a non-disabled path. See section 5.1 for details.
3.4 Performance Guidelines
When creating a dump configuration to optimize for performance, remember that there are three
mechanisms for reducing system dump time: selection, compression, and parallelism. Selection
can be enabled independently of the other two, and can significantly reduce the size of memory
to be dumped and thus the overall dump time. Compression and parallelism can also be
independently enabled, but there are interactions and tradeoffs between them since compression
requires more CPU resources and can thus limit the available parallelism.
Given a particular level of available parallelism, the actual dump time reduction as the number of
dump units increases will depend on a number of factors, including:
• How much hardware overlap there is between paths to devices in different dump units.
• Whether or not compression is enabled.
• Varying device or HBA or link speeds across the different dump units.
Each of these factors is discussed below.
4
The scsimgr(1m) command can be used to disable a lun path. The specific command to disable a lun path is
scsimgr disable -H <lun path hw_path>
Note that this disables the lun path for normal access at run-time, which should be fine for a dedicated dump device but may not be for a
device shared with swap or root for example.
Config
uration of Dev2
before Dev 1
can result
in only 1 of the 2 HBA ports being used.
D1
Figure
11
–
Dev
2 then Dev1
Figure
12
–
Dev1 then Dev2
Configuration Ordering in HBA Selection
hba1
hba2
Dev1
Dev2
Use of both HBA ports can be
accomplished
by configuring Dev1 before Dev2, or by
disabling the path from hba1 to Dev2.
D1
hba1
hba2
Dev1
Dev2
D2
(black line)
=
Unused path
(red line)
=
Configured dump path