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Startup Command and Parameter Reference
Startup Parameter Descriptions : Message Buffer Size (-Mm)

Message Buffer Size (-Mm)

Use Message Buffer Size (-Mm) to specify the standard message buffer size, in bytes. This parameter is relevant only for network client/server connections. Message Buffer Size (-Mm) can be specified by both the client and the server, however the size of the message buffer specified by the server takes precedence; a value specified by the client is used as a suggestion for initial buffer allocation, but the client then adopts the server value when the connection is initiated.
Operating system and syntax
UNIX / Windows
-Mm n
Use with
Maximum value
Minimum value
Single-user default
Multi-user default
Client Connection, Database Server
The message buffer size.
OpenEdge uses message buffers to move records (messages) between servers and remote clients. Records (plus 40-byte headers) larger than the message buffer size are fragmented into multiple messages. If your database records are large, increase this parameter to avoid record fragmentation. However, if the network works more efficiently with small messages, reduce -Mm and fragment larger records.
Note: Prior to OpenEdge Release 11.6, the value of -Mm had to agree between the client and server or the connection would be refused. Going forward, in addition to not requiring agreement between client and server, clients can also connect to multiple databases with different -Mm values obtained from the server. To enforce the earlier behavior, use Enforce Mm (-enforceMm).