PMDF System Manager's Guide

PMDF normally creates one delivery service job per channel that needs service. This applies to both immediate service and periodic service jobs: when a message is initially sent and immediate service is needed one job is created for each channel to which the message is queued, and when PMDF creates periodic jobs it normally creates one periodic job for each channel that needs service.

A single service job may not be sufficient to insure prompt delivery of all messages, however. In particular, PMDF-FAX messages may take a long time to deliver; if multiple FAX modems are available it is not sensible to use a single job and a single modem.

The addrsperjob and filesperjob keywords can be used to cause PMDF to create additional service jobs. Each one of these keywords takes a single positive integer parameter which specifies how many addresses or queue entries (i.e., files) must be sent to the associated channel before more than one service job is created to handle them. If a value less than or equal to zero is given it is interpreted as a request to queue only one service job. Not specifying a keyword is equivalent to specifying a value of zero. The effect of these keywords is maximized; the larger number computed will be the number of service jobs that are actually created.

The addrsperjob keyword computes the number of services jobs to start by dividing the total number of To: addressees in all entries by the given value. The filesperjob keyword divides the number of actual queue entries or files by the given value. Note that the number of queue entries resulting from a given message is controlled by a large number of factors, including but not limited to the use of the single and single_sys keywords and the specification of header-modifying actions in mailing lists.

The maxjobs keyword places an upper bound on the total number of service jobs that can be created. This keyword must be followed by an integer value; if the computed number of service jobs is greater than this value only maxjobs jobs will actually be created. The default for this value if maxjobs is not specified is 100. Normally maxjobs is set to a value that is less than or equal to the total number of jobs that can run simultaneously in whatever service queue or queues the channel uses.

For example, if a message with 4 recipient addresses is queued to a channel marked addrsperjob 2 and maxjobs 5 a total of 2 service jobs will be created. But if a message with 23 recipient addresses is queued to the same channel only 5 jobs will be created because of the maxjobs restriction.

Note that these keywords affect the creation of both periodic and immediate service jobs. In the case of periodic jobs the number of jobs created is calculated from the total number of messages in the channel queue. In the case of immediate service jobs the calculation is based only on the message being entered into the queue at the time.

Finally, note that the addrsperjob keyword is generally only useful on channels that provide per-address service granularity. Currently this is limited to PMDF-FAX channels. See <REFERENCE>(HEAD3_FAXMULTIMODEMS_SCHED) for further information on using these keywords with PMDF-FAX.