DB2 Version 9.7 for Linux, UNIX, and Windows

buff_total - Number of currently allocated FCM buffers monitor element

Number of fast communication manager (FCM) buffers currently allocated. This number includes both in-use buffers and free buffers.

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

If the buff_auto_tuning monitor element indicates that FCM is being tuned automatically, then the value of the buff_total monitor element is adjusted based on the demand for FCM buffers.

To determine the number of FCM buffers currently in use, use the following formula:

buff_total - buff_free

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.