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## About Manual Scans and Scheduled Scans on Cluster Servers

### Node-based Scanning

The Manual and Scheduled Scans are node based. This means, only one manual or scheduled scan can be run on one node at the same time.
Example: Virtual servers A and B are on node1; if one scanning task is running on A, then B cannot run a background scan at the same time.

### Scans During a Failover or Following a Real-time Scan Change

During a failover period on clusters, the database of the Information Store will be unmounted and mounted by another node. After failover, manual or scheduled scan tasks stop. This is also true when the real-time scan status changes on the same node (as a result of enabling or disabling virus scanning, attachment blocking, or content filtering).
Example 1: Virtual servers A and B are on node1. If server A has a failover to node 2, the scan task running on server B will stop.
Example 2: Virtual servers A and B are on node1. If server A turns off real-time scanning (that is, disables all filters), the scan task running on server B will stop.