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1-36 IBM Informix OnLine Database Server Administrator’s Guide
Shared-Memory Parameter Guidelines
The recommended value for LOGBUFF is 16 pages, or 16 multiplied by
BUFFSIZE.(BUFFSIZE is the machine-specific page size and the last parameter
listed in tbconfig.std.) The default value is 32KB.
LOGSMAX
LOGSMAX specifies the maximum number of logical log files that OnLine
supports. OnLine requires at least three logical log files for operation. In
general, you can set the value of LOGSMAX equal to the value of LOGFILES.If
you plan to relocate the logical log files out of the root dbspace after you
initialize OnLine, assign
LOGSMAX the value of LOGFILES, plus 3. The reason
for this is explained on page 3-31, which describes how to move the logical
log files to another dbspace.
The default value of LOGSMAX is 6. The maximum number of logical log files
that you can display using DB-Monitor is 50. (You can display any number of
log files using the tbstat utility.)
CLEANERS
CLEANERS specifies the number of additional page-cleaner daemon
processes available during OnLine operation. (By default, one page-cleaner
process is always available.)
A general guideline is one page cleaner per physical device, up to a
maximum of eight. You might be able to tune the value to achieve an increase
in performance. Refer to page 5-19.
The maximum value for CLEANERS is 32. The minimum value is 0. The
default value is 1. (The value specified has no effect on the size of shared
memory.)
SHMBASE
SHMBASE specifies the base address where shared memory is attached to the
memory space of a user process. Do not change the value of SHMBASE. The
default value for SHMBASE is platform-dependent. DB-Monitor does not
prompt for this value during initialization. For more information about the
role of SHMBASE in initialization, refer to page 2-26.