Average Synchronous Read (ms) - Table Space

Identifier:db2.tbsp_avg_sync_read_time

Database Object Monitored:Table Space

Category:Buffer Pool and I/O

Description:Average synchronous read time

Equation:db2. tbsp_sync_read_time / db2. tbsp_sync_data_reads

Usage Notes:This variable indicates the time that your application must wait for synchronous I/O read activity. Synchronous reads can occur for two reasons:

The database determined that an asynchronous (prefetched) read was not possible.

The database attempted a prefetched read but the prefetch request was denied.

If the second case is true, you can improve performance by tuning the prefetch parameters so that prefetching can be performed. If the database attempted a prefetched read pool_async_data_read_reqs will be >0. If some of these attempts failed pool_async_data_reads will be < pool_async_data_read_reqs.

If the above is true, the recommended action is:

Ensure that the sequential detection flag database configuration parameter (seqdetect) is set ON

Ensure that the number of prefetchers (num_ioservers) is appropriate

Increase the prefetch size of the tablespace (or the default prefetch size, dft_prefetch_sz, for all tablespaces in that database).

Note:

For multiple buffer pools, the data is combined and only the aggregate number is returned.