1. By Joseph Amrith Raj
WebSphere Application Server v8 Primer
Chapter
7

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JOSEPH’S WEBSPHERE LIBRARY
WebSphere Application Server v8 Primer, part-7: High Performance Extensible Logging [HPEL]
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Table of Contents
1. What is HPEL ? ..............................................................................................................................4
2. Managing HPEL ..............................................................................................................................5
2A. HPEL Log Configuration .............................................................................................................6
2B. HPEL Trace Configuration ..........................................................................................................7
2C. HPEL Text log configuration ......................................................................................................8
3 .Verifying and viewing HPEL ............................................................................................................9
4 .Log viewer command-line tool ...................................................................................................... 11
4A .Some examples of using logviewer command ......................................................................... 11
Use of tail with logviewer ......................................................................................................... 11
Exporting only SysOut events to a readable log ......................................................................... 12
Exporting a log file between some dates ................................................................................... 12
About Author ................................................................................................................................... 13
Connect With US .............................................................................................................................. 14

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1. What is HPEL ?
HPEL – High Performance Extensible Logging, a new log and trace technology in WebSphere Application server v8. It improves the performance of the log and trace as well as access to the data. HPEL provides a convenient mechanism for storing and accessing log, trace, System.err, and System.out information produced by the application server or your applications.
The information [logging/trace] from the HPEL is stored in binary format not the regular text format. You can use the tools like logviewer to convert these logs to the readable text format.
HPEL provides different repositories for storing log and trace information.
A log data repository to store the log records from System.out, system.err,java.util.logging. Trace data repository to store trace records. A text log file, for convenience of reading the log without using the log viewer. You can disable the text log, if you are concerned about the performance.
Some important notes about HPEL
 Every server process has its own set of repositories for logs, trace and text file. Hence there is not sync activity between processes.
 The data written to these repositories is not formatted for reading. In general, formatting data requires some processing. So by not doing it, you are improving performance
 By default, log and trace data is stored in an 8KB buffer before being written to disk. If the buffer is filled within 10 seconds, the buffer is written to disk. If the buffer is not filled within that time it is automatically written to disk to ensure that the logs have the most current information.

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2. Managing HPEL
By default, HEPL is not enabled. To switch to this new logging system, navigate to Troubleshooting logs and trace  server and click on “Switch to HPEL mode”
After you switch to HPEL mode…
As you can see in the above screenshot, you can configure HPEL logging, HPEL trace and HPEL text log.

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2A. HPEL Log Configuration
 Directory path: directory where the logs will be stored/ repositories are placed
 Enable Log record buffering: logs are first written to 8KB buffer before being written to the disk.
 Start new log file daily at: log rotation policy
 Log Record purging policies
o Begin cleanup of oldest records
 When log size approaches max size - automatic log file cleanup to begin when the total size of the log repository approaches the configured maximum size
 When oldest log reaches age limit - automatic log file cleanup to begin when log content is the age limit specified
 When either age or size restriction is met - automatic log file cleanup to begin when either of the previous conditions is met
 Log record age limit: the lifespan, in hours, that log records can remain in the log repository before the log records can be automatically deleted by the server
 Max log size: maximum total size, in megabytes, that the server allows the log repository to reach
 Out of space action
 Stop Server - server stops when the server is unable to write to the log repository
 Purge old logs - server continues to run, and that the oldest log records are immediately removed when the server is unable to write to the log repository
 Stop logging - server continues to run, but that the server cannot continue to write to the log when the server is unable to write to the log repository

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2B. HPEL Trace Configuration
You can either write the trace data to a directory or to memory buffer. When using write to directory option, the configuration options are same as those of HPEL log configuration, as explained above.
In the runtime tab of the Trace configuration, you find a Dump button when select trace to a memory buffer option which writes the contents of the trace memory buffer to the trace directory.
Save runtime changes to configuration as well check box, when enabled.. Specifies that changes are made to both the dynamic state of the running server, and the server configuration, which takes effect on the next restart.

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2C. HPEL Text log configuration
Apart from the configuration options explained in the HPEL log configuration section, you have 2 additional options here.
 Text output format:
o Basic to specify a shorter, one-line-per-record format.
o Advanced to specify a longer format using full logger name and more details about each record.
 Include Trace records: Specifies whether trace records are included in the text log file, as well as log records.
After all the configurations are done.. Save the changes and restart server.

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3 .Verifying and viewing HPEL
I’ve marked 3 sections in the above screenshot to observe after HPEL is enabled and in action.
1. Go to the directory where the log records are being written and check the new HPEL log directory structure.
2. In the administration console, click on the view HPEL logs and traces. Here you can select what content you would like to see: SystemOut, SystemErr and log&trace. Also you can retrieve the log data related to a particular time period. You can also export the log in binary format and

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basic/advanced text log format. Also
3. If you want to switch back to the regular logging method.. you can click on “change log and trace mode” option and then select switch back to Basic mode.

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4 .Log viewer command-line tool
You can use the LogViewer command to query the contents of the High Performance Extensible Logging (HPEL) log and trace repositories
Logviewer command has many optional parameters like RepositoryDir, format, outlog, start date, stopdate etc.. [You can find the complete list of options on infocenter here]
You can also use the logviewer to view new log and trace repository entries as the server writes content to them.
4A .Some examples of using logviewer command
Use of tail with logviewer
Note: when you run logviewer from the bin directory of the profile.. you don’t need to mention the repository directory. Otherwise, you need to mention the optional parameter ‘repositoryDir’ on all logviewer commands.

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Exporting only SysOut events to a readable log
Exporting a log file between some dates

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About Author
Joseph Amrith Raj is a technical consultant for multiple WebSphere products. He worked on various product consulting and support teams including WebSphere Application Server, WebSphere MQ, WebSphere Message Broker, Enterprise Service Bus and WebSphere Process Server. He has 7 years of experience in administration, troubleshooting, consulting and he has significant experience in architecture, strategy and leadership positions. He is IBM certified for WAS, WMQ, WPS , SOA and Cloud Computing.

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