TS/MP 2.5 System Management Manual

steps for each server class in your application, then add the totals to determine global limits for
such attributes as MAXSERVERPROCESSES.
Note that although the calculations and formulas that follow are intended to assist you in arriving
at an optimum configuration, they are necessarily generic. Only you know the specific characteristics
of your system. As a best practice, when utilizing these formulas is that you will pay a small
penalty—in unused resources—if you overconfigure your system. On the other hand, you will pay
a large penalty—in performance and operations problems and obscure system errors— if you
underconfigure your system.
Links and Link Attributes
A link is a connection between a link manager, that is the ACS subsystem processes, and a specific
server process. The link is used to send a request to, and receive a reply from, a server.
ACS subsystem processes share a link among the multiple Pathsend processes executing in the
processor of the ACS subsystem processes. Only one Pathsend process at a time can use the link
(for example, by calling the SERVERCLASS_SEND_ procedure).
A link manager attempts to use one of its existing links to satisfy a send request. If no such link is
available, then the link manager does one of these:
• If the link manager can get a static link, it asks for a link immediately.
• If the process cannot get a static link, and no links become available in the period of time
specified in the CREATEDELAY parameter, then the link manager asks for a link to a dynamic
server process. Dynamic server processes are temporary processes that the PATHMON process
starts as needed and that run only as long as the TCPs or ACS subsystem processes require
them.
The PATHMON process will use all existing server processes (both static and dynamic) before
starting another server process. First, all links for the static server processes are allocated. Then for
each dynamic server process, all links available to the server process (indicated by MAXLINKS)
are granted prior to starting another server process. This can lead to contention for the dynamic
server process.
If there are insufficient links available, the PATHMON process generates a LINK DENIED message
to the log file (for the first occurrence of this problem).
You can change the number of links by changing the server class attribute MAXLINKS or, preferably,
you can add static servers. It is recommended that you configure for enough static servers so that
your application will need to employ few, if any, dynamic servers.
At startup time, to ensure that all static servers are started and, consequently, links are evenly
spread, issue a START SERVER * command prior to starting any Pathsend processes or, if you
use Pathway/iTS, any TERM objects.
To specify information about links, use these attributes of the SET SERVER command:
• “MAXSERVERS” (page 68)
• “MAXLINKS” (page 68)
• “LINKDEPTH” (page 68)
• “NUMSTATIC” (page 68)
• “CREATEDELAY and DELETEDELAY” (page 69)
The PATHMON process creates server processes to create links. Consequently, the value you
specify for the SET PATHWAY MAXSERVERPROCESSES command also affects your link
configuration. For more information, see “Specifying Limits” (page 53).
Configuring Links for Optimum Performance 67