Load Statistics Logs (SAP Library - ITS Tuning and Troubleshooting Guide)

Load Statistics Logs

Load statistics logs contain information about the load, including workthread usage and user session activity, handled by all the AGate processes currently running.

This information, which is written to the load statistics log file about once per minute, helps you to identify high loads at your site, and fine-tune your ITS installation accordingly.

Load statistics logs are stored on your hard disk in files called loadstat.log (or loadstat_*.log in the case of archived versions) under:

C:\program files\sap\its\2.0\<ITS instance>\logs

Each entry in the load statistics log file consists of two lines containing information similar to the following:

2000/12/12 10:15:04.186: 0: w=1.0 s=64/64 w=4/4 h/s=0.000 tat=0.0002000/12/12 10:15:04.186: Total 1: 64/64 req#=1

The table below describes the elements of the first line of the log file entry:

Element	Description
2000/12/12 10:15:04.186	Timestamp.
0	AGate process number. AGate processes are numbered from 0.
w=1.0	This first w value depends on the AGate process session load, workthread activity and a value representing the average load caused per user request within the sampling time of 1 minute. A completely idle system has the value w=1.0 As the load increases, the value of w decreases If there are multiple AGate processes, the ITS Mapping Manager assigns new session requests to the process with the highest w value. In "normal" load situations, only one process is used. The ITS Mapping Manager starts using a second process only if one process is overloaded. Each AGate process maintains a memory-based cache and highest cache hit ratios, so the best performance is achieved using only one process.
s=64/64	The s value displays the ratio of available/maximum sessions. You can use this value for session tuning.
w=4/4	This w value displays the ratio of available/maximum workthreads. You can use this value for workthread tuning.
h/s=0.000	Hits per second.
tat=0.000	Transaction turnaround time. This is the time from the point at which a workthread is enqueued until the point at which it is dequeued, not including the time spent between the ITS and the Web browser. This time corresponds to the average T6 – T1 time according to the timestamp definition described above. It is the average processing time for a request in the AGate process.

A theoretical request throughput maximum is reached if

h/s * tat / (maximum threads) = 1

An AGate process is overloaded if one of the following three conditions applies:

h/s * tat / (maximum threads) > 1

s = 0 All available sessions are used up

w = 0 All workthreads are occupied by session requests

If any of these three conditions applies, users may get errors in the Web browser and experience slow response times. In this case, further ITS tuning is required (provided no other errors are apparent in R/3 or on the network).

The table below describes the elements of the second line of the log file entry:

Element	Description
2000/12/12 10:15:04.186	Timestamp.
Total 1	Total number of AGate instances currently running.
64/64	Number of available/maximum sessions.
req#=1	Number of requests handled since the last ITS (re)start.

To define the handling of load statistics log files or change the location of the logs directory, see Setting Log File Parameters.