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HP-UX 11i v3 Crash Dump Improvements

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D1
Uncompressed
= dump device(s) assigned to dump unit
= available CPUs = CPUs assigned to a dump unit
C
ompressed
o Devices controlled by concurrent dump drivers: each “concurrent device” can
be accessed in parallel. Each can therefore be assigned to a separate dump
unit, even if configured through a single HBA port.
o Logical volumes configured as dump devices (e.g., in an LVM environment): all
logical volumes which reside on the same physical device (LUN) are assigned
to the same dump unit.
2
o Shared swap/dump devices: while there is no restriction on the creation of
dump units with shared swap/dump devices or volumes, see section 3.4.4
recommending against their use with parallel dump.
• Platform support:
o Must be Integrity platforms in the initial HP-UX 11i v3 release.
These requirements can be distilled into the following formulas for calculating the number of dump
units that can be achieved:
CPU Parallelism = (number of CPUs available at dump time) / (1 or 5, depending on
whether or not compression is enabled)
Device Parallelism = (number of reentrant dump HBA ports) + (number of concurrent dump
devices) + (1 if there are any legacy dump devices)
Number of Dump Units = Minimum (CPU Parallelism, Device Parallelism)
The term “reentrant dump HBA port” in the Device Parallelism formula is defined in Section 2.
The number of reentrant dump HBA ports is the number of HBA ports through which reentrant
dump devices are configured.
Examples illustrating parallelism and the use of these formulas are given in the next section.
3.2 Parallelism Examples
In the diagrams below each box with 16 circles represents a 16 CPU system. Uncompressed
dump units are designated by a single CPU, and compressed dump units by a group of 5 CPUs,
using the labels D1, D2, … to denote the various dump units.
3.2.1 CPUs and Dump Units
Figure 1 illustrates the relationship between CPUs and dump units. In uncompressed dump each
dump unit is comprised of one CPU. In compressed dump each dump unit is comprised of five
CPUs.
2
It is important to emphasize that configuring multiple dump volumes on a single physical volume will not allow for parallelism. Parallelism
at dump time can only be achieved across multiple physical devices (LUNs).
Figure 1 – CPUs per Dump Unit
D1