Frequent DAG failovers in a virtualized Microsoft Exchange environment on VMware vSphere

Running Microsoft Exchange in a virtualized environment provides a lot of extra flexibility and even increased availability when running in a HA configuration. This short article is dedicated to some extra tuning that might be necessary in your environment.

The environment I’m talking about is consisting of 2 virtual Exchange 2013 servers, running on VMware vSphere 5.5. Storage is provided by an iSCSI-based array. Compute by HP Gen6 Intel-blades.

Ever since these servers are running, a failover is triggered by the Microsoft Cluster Service, failing all the active mailbox databases over to the second Exchange server. It seems that a snapshot creation task is triggering this failover. As we are using Veeam for backups, we contacted them to ask if there are any workaround for this issue.

Veeam released this following KB article, telling you how to decrease the cluster sensitivity and prevent the failovers to happen. In our case, these settings sadly didn’t solve our issues.

What seems to be the problem, are dropped network packets from within the Guest OS. Following this KB article by VMware, it seems there are some issues with the VMXNET3 NIC on systems that have high traffic bursts (like Exchange).

For now, these settings seem to solve our issue and no failovers are happening again, but if it arises again, I will definitely update this article.

Hopefully both possible solutions by Veeam and VMware can help you in case you are running into the same issue.

Got feedback? Please leave it below!

VMware vExpert 2015 Announcement


Just one hour ago the new list of vExperts was published and contains over 1000 entries! Wow!

In one of my previous articles of last year (VMware vExpert 2014 Announcement), you can find out more information about the vExpert program.

The vExpert 2015 list is published here. Go ahead and see if you made it to the list if you were a candidate to become a new or returning vExpert!

Lastly I would like to congratulate everyone that made it to the list. If you haven’t been selected as vExpert, be sure to try again in the second voting period.

Special congrats go to the following colleagues and friends, in alphabetical order:

Special thanks go to Corey Romero and the VMware Social Media & Community Team for making the vExpert program such a success and fun to be in.

Oh and almost forgot to mention; I’m in for the second year as a vExpert, YAY! =)

Monitoring done differently. A closer look at PRTG Network Monitor

Monitoring your environment, whether it’s physical or virtual is very important. There are numerous tools available that can help you by keeping an eye on your systems and inform you when something is wrong, or even tell you before disaster strikes.

In this article, I will be zooming in to PRTG Network Monitor, a monitoring solution supporting an impressive amount of applications and platforms. Read on to learn more about this awesome product!

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