Don't Be Confused VMware HA != VMotion • Chris Colotti's Blog

Don’t Be Confused VMware HA != VMotion

confusion

Okay, this may sound like something of the most basic things to know, but I am posting this as I still hear how these two things are used interchangeably.  In most cases, it has to do with trying to design a multi-site vSphere deployment where you are trying to let the VMware technology solve the problem of designing for application failure.  What I mean is that when dealing with AWS regions we all know you need to architect the application to run in multiple regions.  When we start dealing with vSphere based clouds, there is some folks that see the use of VMware HA and VMotion as something that will automatically protect their application.  For those that have taken even the most basic VMware certification for VCP, you know these three things are not the same.  One has nothing to do with the other, and designing your application for high availability is not always readily solved with either of the two features.  You are still in some cases responsible for good application design.

Let’s remember that VMware HA is availability protection between hosts in the same cluster.  Most often that cluster is in the same data center, but it could be a stretched cluster between two data centers.  In that case you could in theory have some availability protection, but the hard part is you’d have to do some creative affinity rules to define the hosts per site, and split the application virtual machines between them.  If you did that you could have something that worked for you.  The other thing you have to remember is HA uses various methods to monitor a hosts availability and some methods if you chose to monitor a virtual machine itself.  IN both cases the restarts are done on a priority basis of Low, Medium, and High only.

vmw-dgrm-vsphere-app-ha-lg

With VMotion it’s a planned movement or an automated one based on workload assignment between hosts in the cluster.  There has been some tests done in the past on long distance VMotion, but it would not ever be an “HA Solution”.  I’d personally classify it in the “Disaster Avoidance” category since you’d maybe be shutting systems down knowingly before some kind of event.  VMotion is never invoked by a host or guest failure, that’s entirely up to VMware HA to control.

vmw-dgrm-vsphere-087b-lg

I may sound like I just jumped on a soapbox, but this is basic VMware vSphere knowledge.  It drives me bananas when I hear things being incorrectly represented about the software.  We all run so fast sometimes we forget the basics or in some cases as people new to the technology we don’t take the time to learn it properly.  I’m stepping down now from the box.  Thank you for indulging me in my rant.

About Chris Colotti

Chris is currently a Principal Architect at Cohesity. In his role he spends the majority of his time supporting Cohesity events and creating outward facing content. He also acts as an active interface between the field and engineering/product management as customer zero in the TAG production lab. Chris is active on the VMUG and event speaking circuit and is available for many events if you want to reach out and ask. Previously to this he spent close to a decade working for VMware as a Principal Architect. Previous to his nine plus years at VMware, Chris was a System Administrator that evolved his career into a data center architect. Chris spends a lot of time mentoring co-workers and friends on the benefits of personal growth and professional development. Chris is also amongst the first VMware Certified Design Experts (VCDX#37), and author of multiple white papers. In his spare time he helps his wife Julie run her promotional products as the accountant, book keeper, and IT Support. Chris also believes in both a healthy body and healthy mind, and has become heavily involved with fitness as a Diamond Team Beachbody Coach using P90X and other Beachbody Programs. Although Technology is his day job, Chris is passionate about fitness after losing 60 pounds himself in the last few years.

2 comments

  1. “It drives me bananas when I here things”…typo, you mean ‘hear’

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