Hi there, 

I've been banging my head against for a while now. We have a "IP less" Exchange 2013 SP1 DAG that's been going great for over a year now. I've noticed that randomly all the databases will failover at various times throughout the day. We've looked into recent changes and nothing seems to stand out.

Here is the results of our CollectOverMetrics.ps1. I can see the failover was automatic and caused by a "PeriodicAction". Any idea where I can dig into next to find this root cause?

• We've looked into the AV - disabled as a test
• We've looked at the backup agent in the server - disabled as a test

Any ideas or suggestions?

Update#1 - Noticed we had several Health check mailboxes that were corrupted similar to the post below. Went through steps to recreate them mentioned in the linked post. 

https://social.technet.microsoft.com/Forums/exchange/en-US/b722da4c-eeeb-4afc-adfa-d5359bbb087c/monitor-mailboxes-corrupted?forum=exchangesvrgeneral

• Edited by TSGzz 9 hours 37 minutes ago

My experience is that this is caused by network problems, which can really be just about anything.

Looking into that.

We have PRTG monitoring the server for any drops. - nothing so far

EqualLogic monitors watching the ISCI network for any drops - nothing so far

Updated the drivers - no luck

I hope you have excluded the iSCSI networks from being DAG networks.