My Exchange 2013 (CU7) servers are logging warning approx. every hour regarding the free available disk space on the Mailbox database volumes in the

Application and Services | Microsoft | Exchange | Managed Availability | Monitoring crimson channel in the eventlog. The threshold for this is set to 175GB, and especially for lab environment this can be too low.

The following event is logged:

Log Name: Microsoft-Exchange-ManagedAvailability/Monitoring
Source: Microsoft-Exchange-ManagedAvailability
Date: 1/22/2015 12:07:46 PM
Event ID: 4
Task Category: Monitoring
Level: Error
Keywords:
User: SYSTEM
Computer: EXCH01.contoso.com
Description:
Database ‘MDB02’ is low on log volume space. ‘MDB02’ is low on log volume space [F:\]. Current=86,97 GB, Threshold=175,78 GB

You can check the Server Health with the “MailboxSpace” healthset:

Get-ServerHealth –Identity EXCH02 –HealthSet MailboxSpace

Which will return all monitors in this healthset. Clearly visible are two Unhealthy monitors. Using a pipe and selecting only the Identity and Alertvalue shows the proper name of the monitor.

We can change this behaviour by creating a monitor override that sets the threshold to 10 GB. For a normal Global Override you can use the –Duration option, which determines how long the threshold will override. This value can be between 0 and 60 days. If you want to change this permanently you can use the –ApplyVersion option.

This value here in the version of Exchange that can be retrieved using the Get-ExchangeServer | Select AdminDisplayVersion cmdlet in Exchange Management Shell.

Add-GlobalMonitoringOverride -Item Monitor –Identity MailboxSpace\StorageLogicalDriveSpaceMonitor -PropertyName MonitoringThreshold -PropertyValue 10 -ApplyVersion 15.0.1044.25

After restarting the Health Manager service on both Exchange server (I have two multi-role in a DAG) the MailboxSpace health set reports ‘healthy’.