HP-UX Virtual Partitions Administrator's Guide (includes A.05.02)

How vPars and its Components Work
vPars Monitor and Database
Chapter 2
32
vPars Monitor and Database
vPars Monitor
For each hard partition, the vPars Monitor manages the assignment of hardware resources to virtual
partitions, boots virtual partitions and their kernels, and emulates certain firmware calls. By emulating
these specific calls, vPars creates the illusion to each HP-UX instance that it is running on a standalone
server, consisting of the hardware that has been assigned to it.
Once a virtual partition is launched, the Monitor transfers ownership of the hardware to the virtual partition.
At that point the Monitor is not involved in accessing I/O hardware, physical memory, or process to processor
cycles: the individual HP-UX instances have complete ownership of their respective hardware resources. This
allows each partition to run at full speed.
The commands for the vPars Monitor are shown in the section “Monitor: Using Monitor Commands” on
page 131; however, most of the vPars operations are performed using vPars commands at the Unix shell level.
For more information on the commands, see the chapter “Monitor and Shell Commands” on page 119.
For information on the vPars Monitor memory usage, see Appendix D, “Memory Usage with vPars in
nPartitions,” on page 361.
vPars Partition Database
At the heart of the vPars Monitor is the partition database. The partition database contains partition
configuration information. Using the partition database, the Monitor tracks which virtual partitions exist
and what hardware resources and partition attributes are associated with each partition.
When the Monitor boots (see “Boot Sequence” on page 33), it reads a copy of the partition database from a file
on the same disk from which the Monitor /stand/vpmon is booted. The default file is /stand/vpdb. Then, the
Monitor creates a master copy of the vPars partition database in the memory reserved by the Monitor.
The operating system of each virtual partition also keeps a local copy of the partition database in a file, by
default /stand/vpdb, on its local boot disk.
You can create, modify, and view the database contents using vPars commands at the Unix shell level. See
“Monitor and Shell Commands” on page 119. Because the format of the database is proprietary, you must use
only vPars commands to create, modify, and view the database.
Whenever you execute a vPars command from the Unix shell of a partition, the change is made first to the
Monitor’s master copy. Then, the operating system from which you executed the command updates its local
copy from the master copy. Every five seconds, the operating system of each running partition automatically
updates its local copy from the master copy. This synchronization ensures that the virtual partitions and
changes to the partition database are preserved when the entire hard partition is rebooted.
NOTE The Monitor can only synchronize to the database files of running virtual partitions. If you
reboot the hard partition, you should boot the Monitor from the boot disk of a virtual partition
that was running during your most recent partition configuration change.