To complete On-Demand Scans in a reasonable amount of time, it helps to limit the size of the data scanned. While an option exists to scan all users (or in Exchange Online, Sites), the size of these scans can prevent them from finishing.
For information on file size, see Maximum File Size for On-Demand Scans.
If the total users or sites is greater than 10,000, do not select the Scan for all users option. Instead, enable the Include the following users option, then consider the following:
- Plan for a maximum of 10,000 users per scan.
- Avoid running more than five scans in parallel.
Here are some best practices on how to segment users:
- Users belonging to a specific AD group. For example, Marketing, Sales, Finance, or other departments.
- Users belonging to a specific AD location. For example, Mountain View, Santa Clara, California, or another geographic location.
- Users with names starting with a letter in the alphabet. For example, you could scan all users with a first name that begins with "A" or all users with a last name that begins with "S".
These options also work with Exchange Online Sites.