The Engines and Performance setting controls how many of the selected engines should be used in order to provide you with an acceptable probability that your system is protected. There is a trade-off between increasing the probability of catching a virus and maximizing your system performance. The more engines you use, the greater the probability that all viruses will be caught. However, the more engines you use, the greater the impact on your system's performance.
You can have a different Engines and Performance setting on different servers, depending on your needs. For example, you might want to use only a single engine on your mailbox server, to maximize its system performance. Then, you can use several engines on your Edge or Hub transport servers.
 Note: |
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| The Engines and Performance setting only applies to virus scanning. It is not used in filtering, spyware scanning, or spam scanning. You must select the policy for each scan (realtime, transport, scheduled, and on-demand) you configure; it is not global. |
To configure the number of scan engines, select from the following Engines and Performance options:
- Scan with all engines—Queues scanning
if any selected engine becomes busy, such as during engine updates.
Depending on the number of engines that you have selected for each
scan job, this option generally increases the probability of virus
catching at the expense of system performance.
- Scan with the subset of engines that are
available—Scans with all selected engines that are available.
Scans continue with the available engines when one of the selected
engines is being updated. Depending on the number of engines that
you have selected for each scan job, this option generally
increases the probability of virus catching but not at the expense
of delays in mail flow.
- Scan with a dynamically-chosen subset of
engines—FPE heuristically chooses from the selected engines,
based on recent results. (Results are determined by when the engine
or its definitions were last updated, and whether the engine
recently incurred any errors.) On average, half of the selected
engines are used in scanning any single object, so this setting can
be seen as a neutral option that does not favor system performance
over virus catching (and vice versa).
- Scan with only one engine—FPE
heuristically chooses only one engine from the selected engines,
based on recent results. (Results are determined by when the engine
or its definitions were last updated, and whether the engine
recently incurred any errors.) This option increases system
performance but is not the optimal setting for catching viruses
since only one engine is used.
Click Save after making any changes to your settings.