Spool Server Selection Example

The following example shows a configuration of logical servers and how this configuration affects the system’s spool server selection.

Server for Local Printing

This server is defined for output devices that are connected with local access methods. As the server selection should be static, the server is not integrated into a hierarchy.

Server for Remote Printing

There is a hierarchy of logical servers for remote printing.

For information about the legend in the screenshot, see Interpreting the Spool Server Display. The individual servers are explained with their definition below.

The LocalProductionPrint Logical Server

The LocalProductionPrint server is defined for time-critical printers, such as production printers, that the SAP System accesses using the local access methods C and L.

The server definition of LocalProductionPrint looks like this:

As the server does not have an alternative server and is load balancing is not enabled, only hs0311_BIN_53 can process output requests for devices that specify the spool server LocalProductionPrint in their device definition.

The ProductionPrint Logical Server

While the LocalProductionPrint server processes requests for time-critical production printers that are connected using local access methods, the ProductionPrint server handles requests for time-critical production printers that the SAP System accesses using the remote access methods U and S, or with the OMS access method E.

The server definition of ProductionPrint looks like this:

This server allows load balancing. Due to this server’s position at the top of the hierarchy of logical servers, its load balancing can draw on all of the spool servers in the BIN SAP System. This strategy is in accordance with the high priority of the output requests. To ensure the fastest possible processing, these requests are allowed to draw on servers reserved for mass printing and desktop printing, as capacity permits.

In load balancing for this server, the spool system searches both the Mapping and Alt. server hierarchies. In the Alt server hierarchy, the spool system evaluates the spool system used for mass printing and desktop printing; the evaluation therefore includes all spool servers in the SAP System.

By contrast, output requests for the logical server VolumePrint cannot access the time-critical spool server, hs0311_BIN_53. This server is exclusively reserved for production printing, while all other servers are shared.

LocalProductionPrint and ProductionPrint separate output devices by their access methods, local or remote. This grouping allows you to distribute output requests for unproblematic remote printers, while keeping a static server assignment for local printers.

If all local printers were defined under the same names in the hosts of other spool servers, then these devices could use alternative servers and/or load balancing as successfully as remote printers can.

The VolumePrint Logical Server

This server is for high-volume line printers, such as those in some computing centers.

The server definition of VolumePrint looks like this:

Load balancing is permitted; this means that output requests sent to it can be distributed among its own server (pcintel_BIN_53) and the DesktopPrint server. Its own server cannot be used for DesktopPrint requests.

If you should decide, for example, that desktop requests should have a higher priority than mass print requests, you only need to move DesktopPrint into VolumePrint’sposition in the hierarchy and change the load-balancing settings in the definitions.

The enabled load balancing also affects ProductionPrint output requests. The server selection procedure is recursive; it uses the same rules at each level of the hierarchy. As the server can distribute its load, load balancing of ProductionPrint requests can take both pcintel_BIN_53 (in the logical server hierarchy) and the DesktopPrint server into consideration as the least-busy server.

If load balancing were not allowed for VolumePrint , then only pcintel_BIN_53 could be considered for ProductionPrint requests. As long as pcintel_BIN_53 is a valid spool server (running, with a spool work process), then the load balancing search would not be allowed to search the Alt server hierarchy at this level.

The DesktopPrint Logical Server

This server is defined for desktop printers whose requests have a low priority. The printers do not have to print large quantities, nor are their requests time-critical.

As the overview at the start of the example shows, this server has a special characteristic:
its alternative server is VolumePrint. This alternative server specification points back upward in the hierarchy. This is necessary to give DesktopPrint a substitute server. The spool system is able to resolve such redundancy correctly; it will not endlessly loop through the DesktopPrint hierarchy if it looks for an alternate server.

The server definition for DesktopPrint looks like this:

Because the server is exclusive, no load balancing is allowed for its output requests. If pn0202_BIN_53 is active, all DesktopPrint output requests are processed there. VolumePrint is checked for an available alternate server only if pn0202_BIN_53 is no longer active.