DB2 Version 9.7 for Linux, UNIX, and Windows

buff_free - FCM buffers currently free monitor element

This element indicates the number of FCM buffers currently free.

Table 1. Table Function Monitoring Information
Table Function	Monitor Element Collection Level
MON_GET_FCM - Get FCM metrics	Always collected

Table 2. Snapshot Monitoring Information
Snapshot Level	Logical Data Grouping	Monitor Switch
Database Manager	fcm	Basic

Usage

To calculate the percentage of free FCM buffers, use the following formula:

(buff_free/buff_total) * 100

If the percentage of free FCM buffers falls below 20% and if the FCM buffer auto-tuning is enabled, then DB2 database manager will adjust the FCM buffer numbers.

If the percentage of free FCM buffers falls below 20% and if the FCM buffer auto-tuning is not enabled, then you need to tune the fcm_num_buffers configuration parameter.