If discovery node that is dedicated to pulling Exchange Online data from Microsoft tenant. Repeatedly, the server's drive that runs the node service is filling up with temporary files to the point that the service no longer can function and crashes.
So, while running the Exchange Online discovery it generate lots of data and filled up the node drive if Collect Mailbox folders and Collect mailbox folder permission options are selected in scope of discovery. If unselect the Collect Mailbox folders and Collect mailbox folder permission options , discovery is running fine and discovery is finished successfully and node drive is not filling up.
The error is stemming from the service repeatedly opening new ExchangeOnline Powershell sessions and downloading "CmdletHelp" xml files (25MB worth) on each connection. These files do not get cleaned up and eventually fill up the drive incredibly quickly.
The issue is due to the version of Exchange Online PowerShell we are using and an existing Microsoft bug.
We are continuing to investigate upgrading to a newer version of this API and hope that includes a fix by Microsoft.
Bug 554624: Temp files from EXO are not being cleaned up if EXO discovery cancels/stops
This bug is being investigated now and triaged to the next release of Enterprise Reporter - 3.5.3.
