Set the DABACON Buffer Size

Each module definition in the System DB may include a BUFFER command. This command specifies how much space is to be reserved for the Database Constructor (DABACON) buffer in each module, and allows the database constructor to trade off CPU usage against disk I/O to some extent and thereby optimize computer efficiency in some of the more heavily used modules.

If the module definition does not include a buffer size, the default buffer size of 5,120,000 words (20MB) is used. The maximum is size is 51,200,000 words (200MB). The modmac macro sets the buffer size for all modules (except the Global daemon) to 12,800,000 words (50MB); the user is advised to leave it at this.

If the environment variable PDMSBUF is defined by a user, this overrides the value from the BUFFER command ‑ this can be used to change the amount of memory used on machines with particularly large or small amounts of free memory.

Users are advised to contact AVEVA Solutions Limited if they have any doubts about the setting of their buffer sizes.

The syntax used to set up the size of a buffer in AVEVA Administration is either:

BUFFER integer(where integer is the required buffer size in words)

when the module definition is being created (for example, in the project module definition macro) or:

EDIT MODULE moduleid BUFFER integer

where an existing module definition is being edited. integer is the number of words to be reserved for the buffer.

The buffer can be reset to its default value at any time. For example:

ED MOD ISODRAFT BUF DEF

would reset the Isodraft buffer size to its default value.