PMDF System Manager's Guide

Critical SYSGEN parameters for overall Dispatcher functioning

The SYSGEN parameter MAXPROCESSCNT must be large enough to accomodate the number of server processes, in addition to any other processes on the system.

Sites running DEC TCP/IP Services (UCX) should set the SYSGEN parameter
CHANNELCNT=Sum_services MAX_CONNS + Sum_services (MAX_CONNS*MAX_PROCS)+30.

Sites running MultiNet or TCPware can avoid the need to change their system's CHANNELCNT by instead setting UCX_HOLD=0 in the Dispatcher configuration file.

SYSGEN parameters relevant for mailbox servers

SYSGEN system minimums and system defaults for quotas can affect the quotas for server processes. SYSGEN parameters especially relevant for PMDF mailbox servers are:
PQL_MASTLM, PQL_DASTLM,
PQL_MBIOLM, PQL_DBIOLM,
PQL_MBYTLM, PQL_DBYTLM,
PQL_MCPULM, PQL_DCPULM,
PQL_MDIOLM, PQL_DDIOLM,
PQL_MENQLM, PQL_DENQLM,
PQL_MFILLM, PQL_DFILLM,
PQL_MJTQUOTA, PQL_DJTQUOTA,
PQL_MPGFLQUOTA, PQL_DPGFLQUOTA,
PQL_MTQELM, PQL_DTQELM,
PQL_MWSDEFAULT, PQL_DWSDEFAULT,
PQL_MWSQUOTA, PQL_DWSQUOTA,
PQL_MWSEXTENT, PQL_DWSEXTENT (limited by WSMAX),
VIRTUALPAGECNT, and CHANNELCNT. Rather than using the SYSGEN values, however, the POP and IMAP servers will preferentially use an explicit quota settings from their Dispatcher configuration file service sections. These SYSGEN values are only used if a Dispatcher quota option has not been set.

The quotas for server processes can be controlled via quota options in the Dispatcher configuration file. The top of the Dispatcher configuration file can define global default quotas, and quota values specific for specific services can be set in that service's definition section in the Dispatcher configuration file.
D_threads = 3 + Sum_services (2+NUM_PORTS + MAX_PROCS*(3+MAX_CONNS)) where ports = number of ports that the service listens on.

The current values of your system kernel parameters can be viewed via the command:

# sysconfigdb -l

or

# sysconfig -q proc

If the current values are not high enough for the sort of PMDF load you expect, you should increase the values using the sysconfigdb utility and then reboot your system so that the increases take effect.

Socket parameters

When permitting a large number of parallel incoming connections---that is when the sum over all services of MAX_PROCS*MAX_CONNS is high---it can be necessary to increase the somaxconn and sominconn socket parameters. These control the maximum number of pending connection attempts per server socket (the maximum depth of the listen() and SYN queues).

Heap size

The system's heap size (datasize) must be enough to accomodate the Dispatcher's thread stack usage. For each Dispatcher service compute STACKSIZE*MAX_CONNS, and then add up the values computed for each service. The system's heap size needs to be at least twice this number.

To display the heap size (i.e., default datasize), use the csh command

# limit

or the ksh command

# ulimit -a

or the utility

# sysconfig -q proc