HP-UX 11i v3 Crash Dump Improvements

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2 Terms and Definitions
General Terms:
HBA Host Bus Adapter. E.g., an I/O card with one or more ports on it for
attachment to Fibre Channel, parallel SCSI, or other mass storage
connectivity to a dump device.
Target A storage device attachment to a mass storage interconnect such as Fibre
Channel or SCSI.
LUN An end device in a mass storage interconnect. A dump device in this paper.
Dump Related Terms:
Dump unit A thread of execution during dump. A dump unit requires its own set of
CPUs, dump devices, and other resources, which are non-overlapping with
other dump units.
Reentrancy Capability of a dump driver to issue multiple I/Os simultaneously, one I/O
per HBA port, during dump.
Concurrency Capability of a dump driver to issue multiple I/Os simultaneously per HBA
port, during dump. In HP-UX 11i v3 this capability means that the driver can
issue I/Os simultaneously to multiple devices under a given HBA port, one
I/O per device.
Parallel Dump The mode in the HP-UX 11i v3 dump infrastructure which enables the
parallelism features.
Reentrant HBA port or device An HBA port or device controlled by a reentrant driver.
Concurrent HBA port or device An HBA port or device controlled by a concurrent driver.
td, mpt, c8xx, ciss, sasd Driver names of various HP-provided dump drivers.
Other Terms:
Multi-pathing The ability to find the various paths to a LUN, and failover to use an
alternate path when a given path fails, and/or to load-balance across the
various paths. HP-UX 11i v3 provides native multi-pathing which is built-in to
the next generation mass storage stack.
3 Performance Improvements
In earlier versions of HP-UX 11i there are two mechanisms available to an administrator to reduce
system dump times: selection and compression. Selection reduces the size of the memory to be
dumped. Compression reduces the size of the data that needs to be written to disk. In HP-UX
11i v3 a third mechanism, parallelism, has been added. Parallelism increases the rate at which
the data can be written to disk.
The parallelism feature is called “parallel dump” or “concurrency mode” in the HP-UX 11i v3
dump infrastructure. In the initial release of HP-UX 11i v3 parallel dump support is dependent on
the platform architecture (HP Integrity versus HP 9000). Parallel dump also has characteristics
which are dependent on the type of dump driver, and on the number of CPUs and configured
dump devices.