The Engines and performance setting (in Antimalware - Realtime and Antimalware - Scheduled) and the Scan engines and performance setting (in Task Library - On-Demand Scan) control 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.
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| These settings only apply to virus scanning. They are not used in filtering or spyware scanning. You must select the policy for each scan (realtime, scheduled, and on-demand) that 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 system performance.
- Scan with a dynamically-chosen subset of
engines—Microsoft Forefront Protection 2010 for SharePoint
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—Microsoft
Forefront Protection 2010 for SharePoint 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.