I need to do the exact same thing.  Exclude monitoring, or at the very least, discard alerts.  There's a metric variable you can use when building discard rules called "InMaintenanceWindow", but I don't know what value it's looking for or how it works.  I can't find any documentation on it.

To exclude a client from monitoring, do the following:

1. Open the policy that monitors the client.
2. On the policy page, under Applies To, open the target of the policy.
3. In the Select computers dialog box, add rule that excludes the client from the policy by selecting exclude computers in, Computers list and entering the computer name:
   
4. Click OK.
5. On the policy page, click Save changes.
6. Go to the client that you want to reboot and update the policy on the client.
   After you update the policy on the client, this computer does not get monitored and you can perform the planned reboot.

Hi Triinu,

This might not be the solution for us since we have multiple policies configured for a single server.

We also need to identify the policy first and then exclude the servers which is not possible for "N" number of servers.

Will this be excluded in the availability report as well?

We need to get the uptime report of the servers everyday/weekly/monthly,etc

You can use [Inv_OS_Operating_System].[Last Boot Up Time]