PMDF System Manager's Guide

Since the messages from PC to PMDF are put in one or more files by a PC program which has no way of notifying PMDF that there are now messages to be processed, PMDF has to poll to see if there are message files to be processed.

There are three ways to automate the polling process; you can have PMDF pick up messages from the PC in one of the following ways:

1. Use pc_post. The preferred way to periodically invoke PMDF to process the PC mail is to use a command procedure (on OpenVMS) or shell script (on UNIX) with the appropriate PMDF commands, and have the procedure run periodically.
   The PMDF-LAN configuration utility¹ generates a PMDF_COM:pc_post.com command procedure (OpenVMS) or a /pmdf/bin/pc_post shell script.
   
   On OpenVMS systems, this pc_post.com command procedure should then be submitted to the MAIL$BATCH queue; e.g., by executing pmdf_submit_jobs.com . The pc_post.com procedure resubmits itself in the same queue based on the time_delay interval you specified in it. At system startup time, pc_post.com is submitted automatically by pmdf_submit_jobs.com.
   
   On UNIX, the pc_post shell script should be scheduled for execution using the cron daemon.
   
   
2. Alternatively on OpenVMS, you can use the Polycenter Scheduler. A sample procedure for use by the OpenVMS Polycenter Scheduler would consist simply of the commands:

   $@PMDF_COM:master cc_local poll !for cc:Mail $@PMDF_COM:master ff_local poll !for Microsoft Mail $@PMDF_COM:master mhs_local poll !for MHS $@PMDF_COM:master wpo_local poll !for WPO

3. Change PMDF's periodic delivery job (the post job) interval.

   Note This method is not recommended unless you are familiar with all the mechanisms involved. The description is somewhat brief, and the mechanisms complex.

   If you do not use any procedure to poll for messages, but you do want the polling to happen more often than the four hour default interval of the PMDF post job, then you can set the PMDF post job's interval to an appropriate value for the PC channel polling and use the period channel keyword on all channels except the PC channels to prevent those other channels from being polled as frequently as the PC channels. Channels to the Internet in particular should not be run more frequently than every 30 minutes in order to comply with the Internet host requirements. More generally, it is often worse than futile and indeed counterproductive to run channels (other than PC channels) at too high frequencies as it simply clutters network bandwidth to "bang" on nodes which, once they become unavailable for mail delivery due to local or network problems, will probably not become available again for at least several hours if not days.
   
   To change the PMDF Post job's interval on OpenVMS, redefine the logical name PMDF_POST_INTERVAL to the desired interval in VMS delta time format, e.g., assuming you want to poll every 10 minutes:

   $ DEFINE/SYSTEM PMDF_POST_INTERVAL "0 00:10:00"

   Be sure to also add such a command to your system startup file or to the site-supplied pmdf_site_startup.com file (but not to pmdf_startup.com directly). Then use the period keyword, as described below.
   
   
   To change the PMDF Post job's interval on UNIX, change its crontab entry; e.g., assuming you want to poll every 10 minutes:

   0,10,20,30,40,50 * * * * /pmdf/bin/post.sh >/pmdf/log/post.log 2>&1

   
   Having changed the PMDF Post job's interval, you then need to use the period keyword on your non-PC channels, as follows:

   1. Add a defaults channel to your PMDF configuration file as the first channel block (i.e., after the first blank line in the PMDF configuration file) to set the default period for all channels to 24 periods; (note that 24 times 10 minutes is equivalent to the four hour default). A blank line should preceed this line as well as follow it.

      defaults period 24

   2. If you group all of your PC channels at the end of the PMDF configuration file or use the include file lan.chans, then find the first PC channel in either pmdf.cnf or lan.chans, and add another defaults channel with period 1 so all channels following this defaults channel will have a period of 1, i.e., 10 minutes. Remember to precede and follow the defaults channel with blank lines here also. Suppose that your PC channel blocks are in a file lan.chans referenced at the bottom of your pmdf.cnf file and that you have a Microsoft Mail channel and a cc:Mail channel. Then your lan.chans should look something like:

      defaults period 1 ff_local master defragment charset8 ibm437 msmail.example.com cc_local master defragment charset8 ibm850 ccmail.example.com