Limits and Reserves | Teradata Vantage - 17.00 - Limits and Reserves - Teradata Workload Management

Teradata Vantageā„¢ - Workload Management User Guide

Advanced SQL Engine
Teradata Workload Management
June 2020
User Guide
You can define system-wide resource limits and reserves in Viewpoint Workload Designer in the Limits/Reserves tab of the General area. These values can be different for each planned environment.
Setting Description
CPU Limit By default, a system uses 100% of CPU resources. However, right after a system upgrade, you could use a lower percentage to mimic response times on the old system. Using a lower CPU limit keeps user expectations in check until the new system has a normal load. You can gradually increase the CPU limit as data and workloads are added to the new system.
I/O Limit By default, a system uses 100% of I/O resources. Teradata recommends that the I/O Limit and the CPU Limit always be set to the same value, for example, if CPU Limit is 85%, set I/O Limit to 85%.
Reserved AWTs under Tactical Reserves This setting reserves AMP Worker Tasks for use by Tactical workloads and SLG Tier 1 expedited workloads. Teradata recommends using this setting only if you are sure that your system has an ongoing AWT shortage. To determine this, take one of the following actions:
  • Enable logging for the ResUsageSAWT table, which shows patterns in AWT use.
  • Monitor current AWT in-use counts with the either of these Viewpoint portlets: Metrics Analysis or Metric Heatmap.

If you find an ongoing AWT shortage, try throttling lower-priority workloads before using the Reserved AWTs option. This option removes more AWTs from general use than you specify. Because there are multiple reserved pools set up based on this reserve count, the number of AWTs removed from the general pool equals (reserve count *2) +2. If you select a reserve of 5 AWTs, 12 AWTs are removed from the general pool: (5*2) +2 =12.

Max AWTs for new tactical work under Tactical Reserves This setting limits the number of AWTs that can process new Tactical work. Teradata recommends using the default of 50 if you specify Reserved AWTs.