DB2 Version 9.7 for Linux, UNIX, and Windows

pool_async_index_reads - Buffer pool asynchronous index reads monitor element

Indicates the number of index pages read in from the table space containers (physical) by asynchronous engine dispatchable units (EDUs) for all types of table spaces.

Table 1. Table Function Monitoring Information
Table Function	Monitor Element Collection Command and Level
MON_GET_BUFFERPOOL table function - Get buffer pool metrics	DATA OBJECT METRICS BASE
MON_GET_TABLESPACE table function - Get table space metrics	DATA OBJECT METRICS BASE

Table 2. Snapshot Monitoring Information
Snapshot Level	Logical Data Grouping	Monitor Switch
Database	dbase	Buffer Pool
Table Space	tablespace	Buffer Pool
Buffer Pool	bufferpool	Buffer Pool

For snapshot monitoring, this counter can be reset.

Table 3. Event Monitoring Information
Event Type	Logical Data Grouping	Monitor Switch
Database	event_db	-
Tablespaces	event_tablespace	-

Usage

You can use this element with the pool_index_p_reads monitor element to calculate the number of physical reads that were performed synchronously (that is, physical index page reads that were performed by database manager agents). Use the following formula to calculate the number of synchronous index reads:

# of sync index reads = pool_index_p_reads + pool_temp_index_p_reads - pool_async_index_reads

By comparing the ratio of asynchronous to synchronous reads, you can gain insight into how well the prefetchers are working. This element can be helpful when you are tuning the num_ioservers configuration parameter. You can calculate the ratio of asynchronous index reads to synchronous index reads by using the following formula:

1 - ((pool_data_p_reads + pool_index_p_reads) - (pool_async_data_reads + pool_async_index_reads)) / (pool_data_l_reads + pool_index_l_reads)

Asynchronous reads are performed by database manager prefetchers.