IBM 000-8697 User Manual

Installation and Initial Configuration

USERS

 specifies the maximum number of user processes that can concur-

rently attach to shared memory. The value can have a large effect on the size
of shared memory because it determines the minimum values for four other
shared-memory parameters (

LOCKS

,

TBLSPACES

,

BUFFERS

, and

TRANSACTIONS

.)

To arrive at a value for

USERS

, specify the highest likely value for the number

of user processes active at any one time plus the value of

CLEANERS,

plus 4.

Add one more user process if you intend to implement mirroring.

The minimum value is equal to the value of

CLEANERS

 plus 4, plus 1 if

mirroring is enabled. The maximum value is 1000. The default value is 20.

(The four required user processes are the master daemon, tbinit; the under-
taker daemon, tbundo; the

DB-M

onitor process, tbmonitor; and one

additional user process to ensure a slot for an administrative process. If you
enable mirroring, an additional mirror daemon is needed.)

The value of

TRANSACTIONS

 refers to the maximum number of concurrent

transactions supported by OnLine.

The minimum value of

TRANSACTIONS

 is the value of USERS. The

maximum value is the number of transactions that can fit into a checkpoint
record, which for OnLine 5.x is 1,364.

By default, OnLine sets the value of

TRANSACTIONS

 equal to the value of

USERS

.

DB-M

onitor does not prompt for this value during initialization. The

default value is appropriate unless you plan to use OnLine in an

X/O

pen

environment. If you are configuring OnLine for use with

IBM I

nformix

TP/XA

, refer to the

anual.

LOCKS

specifies the maximum number of locks available to OnLine user

processes during processing. The number of locks has a relatively small effect
on the size of shared memory. The minimum value for

LOCKS

 is equal to 20

locks per user process. The maximum value is 8 million. The default value is
2000.