fcm_num_channels - Number of FCM channels configuration parameter

Configuration type

Database manager

Applies to

• Database server with local and remote clients
• Database server with local clients
• Partitioned database server orDB2® pureScale® database server with local and remote clients
• Satellite database server with local clients

Parameter type

Configurable online

Propagation class

Immediate

Default [range]

UNIX 32-bit platforms

Automatic, with a starting value of 256, 512 or 2048 [128 - 120000 ]

UNIX 64-bit platforms

Automatic, with a starting value of 256, 512 or 2048 [128 - 524288 ]

Windows 32-bit

Automatic, with a starting value 10000 [128 - 120000 ]

Windows 64-bit

Automatic, with a starting value of 256, 512 or 2048 [128 - 524288 ]

The default starting values for different types of servers are as follows:

• For database server with local and remote clients, the starting value is 512.
• For database server with local clients, the starting value is 256.
• For partitioned database environment servers with local and remote clients, the starting value is 2048.

Fast communication manager (FCM) buffers are used for both inter-member and intra-member communications by default. To enable non-clustered database systems to use the FCM subsystem and the fcm_num_channels parameter, you had to set the intra_parallel parameter to YES

An FCM channel represents a logical communication end point between EDUs running in the DB2 engine. Both control flows (request and reply) and data flows (table queue data) rely on channels to transfer data between members.

When set to AUTOMATIC, FCM monitors channel usage, incrementally allocating and releasing resources as requirements change.