When the latest version of a full pattern file is available for download from the Trend Micro ActiveUpdate server, 14 "incremental patterns" also become available. Incremental patterns are smaller versions of the full pattern file that account for the difference between the latest and previous full pattern file versions. For example, if the latest version is 175, incremental pattern v_173.175 contains signatures in version 175 not found in version 173 (version 173 is the previous full pattern version since pattern numbers are released in increments of 2. Incremental pattern v_171.175 contains signatures in version 175 not found in version 171.
To reduce network traffic generated when downloading the latest pattern, OfficeScan performs component duplication, a component update method where the OfficeScan server or Update Agent downloads only incremental patterns.
Component duplication applies to the following components:
Virus Pattern
Spyware Pattern
Spyware Active-monitoring pattern
Virus Cleanup Template
IntelliTrap Exception Pattern
Updating a component as soon as a new version is available reduces the impact of component duplication on server performance. Therefore, make sure you download components regularly.
To help explain component duplication for the server, refer to the following scenario:
|
Full patterns on the OfficeScan server |
Current version: 171 Other versions available: 169 167 165 163 161 159 |
|
Latest version on the ActiveUpdate server |
Full pattern version: 175 Incremental patterns: 173.175 171.175 169.175 167.175 165.175 163.175 161.175 159.175 157.175 155.175 153.175 151.175 149.175 147.175 |
The OfficeScan server compares its current full pattern version with the latest version on the ActiveUpdate server. If the difference between the two versions is 14 or less, the server only downloads the incremental pattern that accounts for the difference between the two versions.
Note: If the difference is more than 14, the server automatically downloads the full version of the pattern file and 14 incremental patterns.
To illustrate based on the example:
The difference between versions 171 and 175 is 2. In other words, the server does not have versions 173 and 175.
The server downloads incremental pattern 171.175. This incremental pattern accounts for the difference between versions 171 and 175.
The server merges the incremental pattern with its current full pattern to generate the latest full pattern.
To illustrate based on the example:
On the server, OfficeScan merges version 171 with incremental pattern 171.175 to generate version 175.
The server has 1 incremental pattern (171.175) and the latest full pattern (version 175).
The server generates incremental patterns based on the other full patterns available on the server. If the server does not generate these incremental patterns, clients that missed downloading earlier incremental patterns automatically downloads the full pattern file, which will consequently generate more network traffic.
To illustrate based on the example:
Because the server has pattern versions 169, 167, 165, 163, 161, 159, it can generate the following incremental patterns:
169.175 167.175 165.175 163.175 161.175 159.175
The server does not need to use version 171 because it already has the incremental pattern 171.175.
The server now has 7 incremental patterns:
171.175 169.175 167.175 165.175 163.175 161.175 159.175
The server keeps the last 7 full pattern versions (versions 175, 171, 169, 167, 165, 163, 161). It removes any older version (version 159).
The server compares its current incremental patterns with the incremental patterns available on the ActiveUpdate server. The server downloads the incremental patterns it does not have.
To illustrate based on the example:
The ActiveUpdate server has 14 incremental patterns:
173.175 171.175 169.175 167.175 165.175 163.175 161.175 159.175 157.175 155.175 153.175 151.175 149.175 147.175
The OfficeScan server has 7 incremental patterns:
171.175 169.175 167.175 165.175 163.175 161.175 159.175
The OfficeScan server downloads an additional 7 incremental patterns:
173.175 157.175 155.175 153.175 151.175 149.175 147.175
The server now has all the incremental patterns available on the ActiveUpdate server.
The latest full pattern and the 14 incremental patterns are made available to clients.
The Update Agent compares its current full pattern version with the latest version on the update source. If the difference between the two versions is 14 or less, the Update Agent downloads the incremental pattern that accounts for the difference between the two versions.
Note: If the difference is more than 14, the Update Agent automatically downloads the full version of the pattern file.
The Update Agent merges the incremental pattern it downloaded with its current full pattern to generate the latest full pattern.
The Update Agent downloads all the remaining incremental patterns on the update source.
The latest full pattern and all the incremental patterns are made available to clients.