I am after some information on Exchange Online Backup with Commvault.
Have you got it working successfully (100% of the mailboxes, 100% of the time)?
Are you running fully cloud or on-prem hybrid?
How many mailboxes are you backing up from the cloud (Exchange Online)?
I am trying to backup 450 mailboxes from Exchange Online and get only 26% through when the errors:
7852 7 02/10 07:53:14 23232 ### CVFetchMessages::Messages - API: FindItems. Exception: [The request failed. The underlying connection was closed: A connection that was expected to be kept alive was closed by the server.]. Attempt number: 
Start filling up the logs.
Commvault support have been investigating and supporting the issue and believe this is a Microsoft throttling issue.
Microsoft are investigating.