HP 3000 Manuals HP 3000 Manuals
Increased Connectivity
by Scott J. McClellan
Commercial Systems Division
This release of MPE XL includes enhancements to the operating system and
networking software that support additional connections. These changes
are summarized below.
* The maximum number of concurrent jobs or sessions has been
increased from 600 to 850 (see further discussion below).
* The maximum number of concurrent processes has been increased from
1559 to 3119.
* The maximum number of terminals connected via Distributed Terminal
Controllers (DTCs) has been increased from 600 to 850.
* The maximum number of remote connections, sometimes referred to as
Virtual Terminal connections, has been increased from 300 to 600.
* Networking software performance has been improved in several key
areas to support the larger number
In determining exactly how many connections can be supported there are a
few critical factors to keep in mind. Each job or direct connect session
requires two system processes. Each remote session requires an
additional system process to act as the data communication server. As a
result, each connection requires either two or three processes, not
counting the process(es) required by user application programs.
The XL Release 3.0 limit of 3119 concurrent processes is a very
significant improvement over prior MPE XL releases. In the past, the
concurrent process limit (1559) forced a distinction between active and
inactive users. The pre-3.0 limit of 600 direct connections assumed that
no more than 50% of the users would be active at any one time. The term
active was defined to mean a user was running an application program. XL
Release 3.0 can support 850 direct connections, with all 850 of them
being active.
Even with the doubling of the process limit it is still possible to run
out of processes. This is particularly true with remote sessions as they
require an additional system process. It could also be true if the
application programs used on your system require more than one process
per connection.
The table below explains how to estimate the concurrent process
requirement for your system. The operating system and networking
software use a variable number of system processes depending on a number
of factors. For the purposes of the calculation below, that number has
been estimated to be 100 (a fairly conservative estimate). The total
number of concurrent processes must be less than or equal to 3119. The
total number of connections must be less than or equal to 850. The total
number of remote sessions must be less than or equal to 600.
Number of Jobs & Sessions _____ (<= 850) x 3 = _____
Number of Remote Sessions _____ (<= 600) x 4 = _____
SYSTEM PROCESSES + + 100
====== =======
Total Connections _____ (<= 850) Total Processes _____ (<= 3119)