IBM Tivoli Monitoring > Version 6.3 Fix Pack 2 > Installation Guides > Installation Guide > Tivoli Data Warehouse solutions
IBM Tivoli Monitoring, Version 6.3 Fix Pack 2
Compressing historical data transmission
The data from the agent or the monitoring server can be compressed before it is transmitted to the Warehouse Proxy Agent. The data is then decompressed at the Warehouse Proxy Agent before it is inserted in the warehouse database, allowing for efficient usage of network bandwith between the historical client and the Warehouse Proxy Server.
The following reductions can occur:
- A reduction in timeout errors due to a low bandwith between clients and Warehouse Proxy Server. Timeout errors on the client side occur when it takes more than 15 minutes for an export of data to complete and be inserted in the warehouse database.
- A reduction in bandwith usage. Uploading historical data to the warehouse can tie up a significant amount of bandwidth, and also impact other critical applications sharing the network link.
- A reduction in the elapsed time for the upload over slow links.
Use this functionality when a slow network is used or when the network is shared with other critical applications. However, compressing the data does increase CPU usage, both at the agent where it is uploaded and at the Warehouse Proxy Agent where it is decompressed. CPU costs differently on a distributed source than on a z/OS source. In a mixed environment, it is possible to enable or disable the compression option (which is a server option), depending on the source operating system of the client. It is also possible to overwrite a server compression option.
Configuration parameters for the Warehouse Proxy Agent are set in the following files according to operating system:
The Warehouse Proxy Agent configuration file now contains two new variables that you can modify if necessary:
- ITM_HOME\TMAITM6\khdenv
For example: C:\IBM\ITM\TMAITM6\khdenv
- ITM_HOME/config/hd.ini
For example: /opt/IBM/ITM/config/hd.ini
- KHD_SERVER_DIST_COMPRESSION_ENABLE
- If this variable is set to Y, then the Warehouse Proxy server allows distributed clients to send compressed data. This variable is set to Y by default.
- KHD_SERVER_Z_COMPRESSION_ENABLE
- If this variable is set to Y, then the Warehouse Proxy server allows z/OS clients to send compressed data. This variable is set to N by default.
The agent configuration file, if historical data stored at the Tivoli Enterprise Monitoring Agent, or the monitoring server configuration file, and if historical data is stored at the monitoring server, accepts a new warehouse variable:
The new Warehouse Proxy Agent variables are visible in a view in the configuration workspace of the Warehouse Proxy Agent. They also exist on the configuration GUI of the Warehouse Proxy Agent.
- KHD_CLIENT_COMPRESSION_ENABLE
- If set to N, and even if the Warehouse Proxy Agent server has allowed the compression, the historical data is not compressed on this source. This variable does not exist by default.
You can see if the compression is occurring by using a tracing level to see the data compressed at the client and uncompressed at the server: ERROR (UNIT: khdxmts DETAIL) in the warehouse proxy agent. To check uncompression in the server log file, see if the file contains the following text:
khdxmts.cpp,154,"KHD_SendBuff_from_xmit_rep") Uncompressing the dataUse ERROR (UNIT: khdxdacl DETAIL) to see the message about compression in the client. To check that the client has overwritten the server variable to not compress the data, see if the file contains the following text:
khdxmts.cpp,167,"KHD_SendBuff_from_xmit_rep" Client did not compress the data
If compression has failed, you will see the following text in the Warehouse Proxy Server log file, khdxrpcs.cpp:
"Client compression failed, data was sent uncompressed"
If compression has failed, you will see the following text in the client log file, khdxdacl.cpp:
"Warehouse client unable to compress the data, data sent uncompressed"
If uncompression has failed, you will see the following text in the Warehouse Proxy Server log file, khdxrpcs.cpp:
"Uncompress error"
If uncompression has failed, you will see the following text in the client log file, khdxdacl.cpp:
"Warehouse client unable to compress the data, data sent uncompressed"
To setup compression:
- Install or upgrade to the newest release.
- Configure the Warehouse Proxy Agent, using the GUI. The GUI can pop up during install time, or can be launched by right clicking on the warehouse Proxy entry in the manage Tivoli Monitoring Services panel. The new server compression variables are part of the GUI and can be modified as needed.
- Compression variables can also be reconfigured using the command-line interface ( itmcmd config hd).
- Compression variables can also be reconfigured in the configuration file itself. Configuration parameters for the Warehouse Proxy Agent are set in the following files according to operating system:
- ITM_HOME\TMAITM6\khdenv
For example: C:\IBM\ITM\TMAITM6\khdenv
- ITM_HOME/config/hd.ini
For example: /opt/IBM/ITM/config/hd.ini
In mixed environments with a previous version of the client and newer version of the server, or new version of the client and a previous version of the server, the compression should not happen.
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Tivoli Data Warehouse solutions