17.00 - AWT Usage Considerations - Teradata Workload Management

Teradata Vantageā„¢ - Workload Management User Guide

Advanced SQL Engine
Teradata Workload Management
June 2020
User Guide

It is normal during busy times to have some AMPs run out of AWTs. This condition often lasts only a second or less. However, system response times degrade if there is a persistent AWT shortage.

If TASM detects an AWT shortage, analyze your corresponding CPU and I/O utilization metrics. Most Vantage systems reach 100% CPU utilization while there are still many AWTs available. Some sites experience peak throughput when as few as 40 AWTs are used. Most likely, the bottleneck is not AWTs, but CPU or I/O resources.

However, an ongoing AWT shortage may indicate an overly busy system. Remember that response time is a function of throughput capabilities and concurrency levels. If a request competes for system resources with 50 other requests at the same priority, it cannot be expected to respond as fast as when it executes alone on the system. Because AWT shortages are a rough gauge of request concurrency levels, you can use them to notify applications or users to expect slow response times. This can sometimes result in decreased user demand because some users postpone issuing their next requests until the system is quieter.