ResUsage and Cache Hit Rates | Teradata Vantage - ResUsage and Cache Hit Rates - Analytics Database - Teradata Vantage

Database Administration

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Analytics Database
Teradata Vantage
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2023-11-03
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lifecycle
latest
Product Category
Teradata Vantage™

ResUsage data can help determine cache hit rates by comparing total logical I/O requests to I/O requests that resulted in a physical I/O. Comparing these helps clarify any confusion that may arise when aligning DBQL data with ResUsage data, since DBQL data only tracks logical I/O.

An analogous circumstance occurs when attempting to differentiate between total BYNET message requests and BYNET message requests that result in a physical BYNET message being sent. Smaller systems see a greater difference between the two because of a higher percentage of point-to-point (PTP) messages with the sender and the receiver being the same node.

In ResUsageSpma table, a logical read count, that is, a count of the total number of requested disk segments for the interval, is represented in the FileAcqs column. The physical read count, or the number of requested disk segments that actually resulted in a read by the I/O subsystem, is represented in the AcqReads and the PreReads columns.

There are similar breakdowns for writes. BYNET logical messages are represented in the columns that begin with Msg, and the physical counterparts are represented with the columns that begin with NetMsg.

Monitoring Memory

Use the ResUsage tables to obtain records of free memory usage and FSG Cache.

Memory Type Monitor With Comments
Free Memory ResUsage See Teradata Vantage™ - Resource Usage Macros and Tables, B035-1099 for more information on using ResUsage macros and utilities to monitor free memory and FSG Cache.
FSG Cache ResUsageSpma

ResUsageSvpr