Yellow Bricks

by Duncan Epping

ha

HA Futures: Orchestrated Restart and Restart Priority – Part 1 of 4 – (Please comment!)

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Last week I visited Palo Alto. I had a long conversation with my friends from the vSphere HA team. I have done a series of articles in the past asking for feedback/comments on future features/functions of HA that the team is looking to implement. One of the first features I would like to discuss is Orchestrated Restart and Restart Priority. Funny enough, this feature is one I discussed in the previous series as well.

For those who don’t know, today you can specify in the vSphere Client what the dependency is between VMs. If a host fails, or multiple hosts fail, and the VMs in a dependency chain are impacted than HA ensures that these VMs are powered on in a particular order. And actually, vSphere HA also has the ability to specify what the restart priority should be of VMs. I described both of these features here. The difference between the two is fairly straightforward though: restart priority are considered “soft rules” and restart orchestration is considered a hard rule. In other words: if one VM can’t be restarted when restart orchestration is used then the next batch will not start.

The UI, to be honest, is confusing, and having two similar concepts that more or less do the same is also confusing. We have discussed various things we would like to have your opinion on. Please leave your feedback in the comments using a valid email address, this way when needed we can follow up.

  • Would you like to have the ability to restart a full chain of VMs, when Orchestration or Priority is enabled and only a few VMs in the chain are impacted by a failure? In other words, would you like to have an option that allows you to restart running VMs that are part of a chain which is impacted by a failure?
  • Would you like to have Orchestrated Restarts / Restart Priority for APD impacted VMs and VM & App Monitoring as well?
  • Would you like to have Orchestrated Restarts and Restart Priority combined in a single feature?
    • Potentially have an option to have multi-level for Orchestration like Restart Priority has
    • Define if it is a “hard” or “soft” rule

And of course, if you feel anything else needs to change about this feature, then please also leave that in a comment. The HA team will be reading this, and are happy to take all feedback they can get. Please help shape the future of HA!

HA Admission control: How can I check how much reserved resources are used?

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I had this question twice in the past three months, so somehow this is something which isn’t clear to everyone. With HA Admission Control you set aside capacity for fail-over scenarios, this is capacity which is reserved. But of course VMs also use reservations, how can you see what the total combined used reserved capacity is including Admission Control?

Well, that is actually pretty simple it appears. If you open the Web Client, or the H5 client, and go to your cluster then you have a “Monitor” tab, under the Monitor tab there’s an option called “Resource Reservation” and it has graphs for both CPU as well as Memory. This actually includes admission control. To verify this I took a screenshot in the H5 client before enabling admission control, and after enabling it, as you can see a big increase in “reserved resources”, which indicates that admission control is taken into consideration.

Before:

After:

This is also covered in our Deep Dive book, by the way, if you want to know more, pick it up.

VMworld Video: vSphere 6.7 Clustering Deep Dive

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As all videos are posted for VMworld (and nicely listed by William), I figured I would share the session Frank Denneman and I presented. It ended up in the Top 10 Sessions on Monday, which is always a great honor. We had a lot of positive feedback and comments, thanks for that! Most importantly, it was a lot of fun again to be up on stage at VMworld talking about this content after 6 years of absence or so. For those who missed it, watch it here:

Also very much enjoyed the book signing session at the Rubrik booth with Niels and Frank. I believe Rubrik gave away around 1000 copies of the book. Hoping we can repeat this huge success in EMEA. But more on that later. If you haven’t picked up the book yet and won’t be at VMworld Europe, consider picking it up through Amazon, e-book is 14.95 USD only.


What happens if all hosts in a vSphere HA cluster are isolated?

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I received this question through twitter today from Markus who was going through the vSphere 6.7 Clustering Deep Dive. And it is fairly straightforward: what happens when all hosts are isolated in a cluster, will the isolation response be triggered?

https://twitter.com/RealRockaut/status/1029652167735631874

I wrote about this a long long time ago, but it doesn’t hurt to re-iterate this. Before triggering the isolation response HA will actually verify the state of the rest of the cluster. Does anyone own the datastore on which the VMs that are impacted by this isolation run? If the answer is no, the ownership of a datastore is dropped during the election, then HA will not trigger the isolation response. I will try to update the book when I have time to include that, hopefully, that means a new version of the ebook will be pushed out to all owners automatically.

Now Available: vSphere 6.7 Clustering Deep Dive book!

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Over the past couple of months Frank, Niels and I have worked ferociously to update the vSphere Clustering Deep Dive. Some of the material was already brought up to date to vSphere 6.0 U2, but the majority was never updated after vSphere 5.1. As you can imagine, this was a tremendous undertaking. Not only did we need to validate every sentence, all diagrams needed to be updated, and with the introduction of the HTML-5 Client also all screenshots had to be retaken. 

Now, just a couple of weeks before VMworld, we are finally at the point where we can press “publish”.

What can you expect? Well, we have said this with previous books, this is not a beginners guide! This is a deep dive, and we aimed to take you in to the trenches of vSphere Clustering technologies. We cover a multitude of different features, and for those who haven’t read the previous books expect the following features to be covered:

  • vSphere HA
  • vSphere DRS
  • vSphere Storage DRS
  • vSphere Storage I/O Control
  • vSphere Network I/O Control

We also have a chapter on stretched clusters, in this chapter we describe how to design and implement a vSphere Metro Storage Cluster, leveraging all of the knowledge gained in the previous chapters.

For your convenience, I copied/pasted some of the Amazon info below.

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  • Paperback: 566 pages
  • Publisher: CreateSpace Independent Publishing Platform; 1 edition (July 29, 2018)
  • Language: English
  • ISBN-10: 1722625325
  • ISBN-13: 978-1722625320
  • Product Dimensions: 5.5 x 1.3 x 8.5 inches
  • Shipping Weight: 1.8 pounds

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I hope all of you will enjoy the book as much as we enjoyed writing it. And before I forget, I want to thank my co-authors for the late night discussions, the hard work, insights and fun/laughter at times.

Get it while it is hot! (Look on the right side column for the links to the book!)