HP Cache Server Appliance Administrator Guide

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Chapter 12 Working with Log Files

• COUNT

• SUM

• AVERAGE

• FIRST

• LAST

You can apply each of these operators to specific fields, requesting it to operate over a specified interval.

Summary logs represent a trade-off between convenience and information granularity. Since you must specify

a time interval during which only a single record is generated, you will necessarily be losing a certain amount

of information. If you want the convenience of summary logs, but also need the detail of a conventional log

file, consider creating and enabling two custom log formats—one using aggregate operators and the other not.

To create a summary log file:

1. Telnet into the HP web cache appliance and select Shell Access as described in Overview of Access

Methods‚ on page 7.

2. Open the

logs_xml.config file located in the Traffic Server’s config directory with Vi.

3. Define the format of the log file as follows:

</Format>

where:

operator is one of the five aggregate operators (COUNT, SUM, AVERAGE, FIRST, LAST). You can

specify more than one operator in the format line.

field is the logging field that you want to aggregate.

n is the interval in seconds between summary log entries.

For more information, see logs_xml.config‚ on page 171.

For example, the following format generates one entry every 10 seconds, with each entry summarizing the

timestamp of the last entry of the interval, a count of the number of entries seen within that 10-second

interval, and the sum of all bytes sent to the client.

</Format>

4. Define a LogObject that uses this format.

5. Save and close the configuration file.

6. Run the command

traffic_line -x to apply the configuration changes.

IMPORTANT You cannot create a format specification that contains both aggregate operators and

regular fields. For example, the following specification would be invalid:

<Format = "%<LAST(cqts)> : %<COUNT(*)> : %<SUM(psql)> :

%<cqu>"/>