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by Duncan Epping

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Unexplored Territory #048: Introduction to Runecast with Stan Markov!

Duncan Epping · Jun 20, 2023 · Leave a Comment

I have mentioned Runecast a fair amount on my blog, dating back to 2017, but somehow I forgot to blog our episode with Stan on the topic of Runecast on the Unexplored Territory Podcast. I just noticed it, so I figured I would share the episode with you folks. I have been a fan of their solution from day 1, and I would encourage people to look and what they have to offer, and of course listen to the episode. Listen via Spotify (https://bit.ly/3Nr16nz), Apple (https://bit.ly/43AlZlB) or the embedded player below!

Performance Management Object reduced availability on stretched cluster

Duncan Epping · Jun 15, 2023 · Leave a Comment

I created a new lab environment not too long ago and I ran into this situation where the Performance Management Object showed up as Reduced Availability with no Rebuild in vSAN Skyline Health. This happened in my case because I created a Stretched Cluster configuration after I had already formed a cluster, which means that the performance management object was randomly placed across hosts without taking those “failure domains” into account. I completely forgot about it until someone on VMTN reminded me about this. I had two options, fix the existing perf database, or simply disable/enable the perf service to it is recreated.

Performance Management Object reduced availability on stretched cluster

As I had no data stored in the database I figured disable/enable is the easiest route. I looked for the option in vSphere 8.0 U1 but could not find it, it seems that the UI option no longer exists for whatever reason. How do I now disable/enable the service? Ruby vSphere Console (RVC) to the rescue!

When you log in to RVC you can simply run the following commands on the cluster object you want to disable/enable the performance service for. Fairly straight forward, and fixed the issue within a minute or so:

vsan.perf.stats_object_delete <cluster>
vsan.perf.stats_object_create <cluster>

I also documented this in the vSAN 8.0 ESA Deep Dive Book by the way, you can buy a paper copy or ebook on Amazon.

vSAN Stretched Cluster failure matrix

Duncan Epping · May 30, 2023 · 1 Comment

The last couple of weeks I was involved internally in a discussion around the different vSAN stretched cluster failure scenarios. I wrote a lengthy email about how vSAN and HA would respond in certain scenarios. I have documented many of these over the years on my blog already, but never really published them as a whole.

vSAN Stretched Cluster failure matrix

In some of the scenarios below, I discuss a “partition”, a partition is a scenario where both the L3 connection to the witness is down and the inter site / inter switch link to the other site for one of the locations. So in the diagram above for instance, if I say that Site B is partitioned then it means that Site A can still communicate with the witness, but Site B cannot communicate with the Witness and cannot communicate with Site A either.

For all of the below scenarios the following applies, Site A is the preferred location and Site B is the secondary location. When it comes to the table, the first two columns refer to the policy setting for the VM as shown in the screenshot below. The third column refers to the location where the VM runs from a compute perspective. The fourth discusses the type of failure, and the fifth and sixth columns discuss the behavior witnessed.

Time to list the various scenarios, and no, it doesn’t include all failures that could occur but should discuss most scenarios which are important for a stretched cluster configuration. Do note, the below-discussed behavior will only be witnessed when the best practices, as documented here and here, are followed. Also note that the table has multiple pages, there are close to 30 scenarios described! If there are any questions feel free to leave a comment, if you feel a failure scenario is missing, also please leave a comment.

Site Disaster ToleranceFailures to TolerateVM LocationFailurevSAN behaviorHA behavior
None PreferredNo data redundancySite A or BHost failure Site AObjects are inaccessible if failed host contained one or more components of objectsVM cannot be restarted as object is inaccessible
None PreferredRAID-1/5/6Site A or BHost failure Site AObjects are accessible as there's site local resiliencyVM does not need to be restarted, unless VM was running on failed host
None PreferredNo data redundancy / RAID-1/5/6Site AFull failure Site AObjects are inaccessible as full site failedVM cannot be restarted in Site B, as all objects reside in Site A
None PreferredNo data redundancy / RAID-1/5/6Site BFull failure Site BObjects are accessible, as only Site A contains objectsVM can be restarted in Site A, as that is where all objects reside
None PreferredNo data redundancy / RAID-1/5/6Site APartition Site AObjects are accessible as all objects reside in Site AVM does not need to be restarted
None PreferredNo data redundancy / RAID-1/5/6Site BPartition Site BObjects are accessible in Site A, objects are not accessible in Site B as network is downVM is restarted in Site A, and killed by vSAN in Site B
None SecondaryNo data redundancy / RAID-1/5/6Site BPartition Site BObjects are accessible in Site BVM resides in Site B, does not need to be restarted
None PreferredNo data redundancy / RAID-1/5/6Site AWitness Host FailureNo impact, witness host is not used as data is not replicatedNo impact
None SecondaryNo data redundancy / RAID-1/5/6Site BWitness Host FailureNo impact, witness host is not used as data is not replicatedNo impact
Site MirroringNo data redundancySite A or BHost failure Site A or BComponents on failed hosts inaccessible, read and write IO across ISL as no redundancy locally, rebuild across ISLVM does not need to be restarted, unless VM was running on failed host
Site MirroringRAID-1/5/6Site A or BHost failure Site A or BComponents on failed hosts inaccessible, read IO locally due to RAID, rebuild locallyVM does not need to be restarted, unless VM was running on failed host
Site MirroringNo data redundancy / RAID-1/5/6Site AFull failure Site AObjects are inaccessible in Site A as full site failedVM restarted in Site B
Site MirroringNo data redundancy / RAID-1/5/6Site APartition Site AObjects are inaccessible in Site A as full site is partitioned and quorum is lostVM restarted in Site B
Site MirroringNo data redundancy / RAID-1/5/6Site AWitness Host FailureWitness object inaccessible, VM remains accessibleVM does not need to be restarted
Site MirroringNo data redundancy / RAID-1/5/6Site BFull failure Site AObjects are inaccessible in Site A as full site failedVM does not need to be restarted as it resides in Site B
Site MirroringNo data redundancy / RAID-1/5/6Site BPartition Site AObjects are inaccessible in Site A as full site is partitioned and quorum is lostVM does not need to be restarted as it resides in Site B
Site MirroringNo data redundancy / RAID-1/5/6Site BWitness Host FailureWitness object inaccessible, VM remains accessibleVM does not need to be restarted
Site MirroringNo data redundancy / RAID-1/5/6Site ANetwork failure between Site A and B (ISL down)Site A binds with witness, objects in Site B becomes inaccessibleVM does not need to be restarted
Site MirroringNo data redundancy / RAID-1/5/6Site BNetwork failure between Site A and B (ISL down)Site A binds with witness, objects in Site B becomes inaccessibleVM restarted in Site A
Site MirroringNo data redundancy / RAID-1/5/6Site A or Site BNetwork failure between Witness and Site A/BWitness object inaccessible, VM remains accessibleVM does not need to be restarted
Site MirroringNo data redundancy / RAID-1/5/6Site AFull failure Site A, and simultaneous Witness Host FailureObjects are inaccessible in Site A and Site B due to quorum being lostVM cannot be restarted
Site MirroringNo data redundancy / RAID-1/5/6Site AFull failure Site A, followed by Witness Host Failure a few minutes laterPre vSAN 7.0 U3: Objects are inaccessible in Site A and Site B due to quorum being lostVM cannot be restarted
Site MirroringNo data redundancy / RAID-1/5/6Site AFull failure Site A, followed by Witness Host Failure a few minutes laterPost vSAN 7.0 U3: Objects are inaccessible in Site A, but accessible in Site B as votes have been recountedVM restarted in Site B
Site MirroringNo data redundancy / RAID-1/5/6Site BFull failure Site B, followed by Witness Host Failure a few minutes laterPost vSAN 7.0 U3: Objects are inaccessible in Site B, but accessible in Site A as votes have been recountedVM restarted in Site A
Site MirroringNo data redundancySite AFull failure Site A, and simultaneous host failure in Site BObjects are inaccessible in Site A, if components reside on failed host then object is inaccessible in Site BVM cannot be restarted
Site MirroringNo data redundancySite AFull failure Site A, and simultaneous host failure in Site BObjects are inaccessible in Site A, if components do not reside on failed host then object is accessible in Site BVM restarted in Site B
Site MirroringRAID-1/5/6Site AFull failure Site A, and simultaneous host failure in Site BObjects are inaccessible in Site A, accessible in Site B as there's site local resiliencyVM restarted in Site B

New book: VMware vSAN 8.0 U1 Express Storage Architecture Deep Dive!

Duncan Epping · Apr 27, 2023 · 9 Comments

We already gave some hints on twitter, and during an episode of the Unexplored Territory podcast, but here it finally is… The new book, the VMware vSAN 8.0 U1 Express Storage Architecture Deep Dive! It has been a year since we released the vSAN 7.0 U3 Deep Dive book, and with this brand new vSAN architecture being introduced in vSAN 8.0 we figured it was time to do a full overhaul of the book as well. Mind you, this new book purely deals with the Express Storage Architecture, aka vSAN ESA. This also means that some of the features which are not supported by ESA are not discussed in this book, for that you will need to buy the vSAN 7.0 U3 Deep Dive book, which covers OSA. Another big change is that we brought in a third author, we asked our good friend Pete Koehler to contribute to the book. Pete had done reviews of previous books, and considering the amount of material he produced for VMware Tech Marketing for vSAN (and ESA specifically) it made a lot of sense to bring him in!

VMware’s vSAN has rapidly proven itself in environments ranging from hospitals to oil rigs to e-commerce platforms and is the market leader in the hyperconverged space. Along the way, the world of IT has rapidly changed, not just from a software point of view, but also from a hardware perspective. With vSAN 8.0 VMware brought a new architecture to market called vSAN Express Storage Architecture (ESA). This architecture is highly optimized for today’s world of datacenter resources, be it CPU, memory, networking, or NVMe based flash storage.

The authors of the vSAN Deep Dive have thoroughly updated their definitive guide to this transformative technology. Writing for vSphere administrators, architects, and consultants, Cormac Hogan, Duncan Epping , and Pete Koehler explain what vSAN ESA is, why the architecture has changed, what it now offers, and how to gain maximum value from it. The book offers expert insight into preparation, installation, configuration, policies, provisioning, clusters, architecture, and more. You’ll also find practical guidance for using all data services, stretched clusters, two-node configurations, and cloud-native storage services.

Although we pressed publish on Tuesday, sometimes it takes a while before the book is available in all Amazon stores, but it should just trickle down in the upcoming 24-48 hours. The book is priced at 9.99 USD for the ebook and 29.99 USD for a paper copy, and is sold through Amazon only. Get it while it is hot, and we would appreciate it if you would use our referral links and leave a review when you finish it. Thanks for the support, and we hope you will enjoy it!

  • paper – 29.99 USD
  • ebook – 9.99 USD

Of course, we also have the links to other major Amazon stores:

  • United Kingdom – ebook – paper
  • Germany – ebook – paper
  • Netherlands – ebook – paper
  • Canada – ebook – paper
  • France – ebook – paper
  • Spain – ebook – paper
  • India – ebook
  • Japan – ebook – paper
  • Italy – ebook – paper
  • Mexico – ebook
  • Australia – ebook – paper
  • Brazil – ebook
  • Or just do a search in your local amazon store!

New book: VMware vSAN 8.0 U1 Express Storage Architecture Deep Dive!

VMUG Advantage Homelab Group Buy Discount offer 2023! (Also for renewals!)

Duncan Epping · Apr 19, 2023 · Leave a Comment

VMUG Advantage Homelab Group Buy Discount offer 2023! (Also for renewals!)It is that time of the year again for many, time to renew your VMUG subscription. The minimum discount you will get is 12% and this can go up to 15% when the number of participant goes above 300, which drops the price down to 170 USD. What do you get when you sign up and buy a 12-month subscription?

  • 365-day Evaluation Licenses
    • Including vSphere 8, vSAN 8, Workstation 17 Pro, Fusion 13 Pro, NSX, vRealize, Horizon, and more!
  • 20-35% discount on training and certification
  • Access to “test drive“
  • Advantage members receive a $ 100 USD VMware Explore discount (not stackable)

The VMUG Advantage Program comes at a cost of 200 USD. Last year the discount was 15%, which means the price ended up being 170 USD for a full year. If you have just one training course planned per year, the VMUG Advantage Program will have already paid for itself (20% discount on a 3000+ USD training course). Yes, I have been talking about USD so far, but of course, this offer is available to all our community members globally (Europe, APJ, Africa, Middle East, etc). Now, again, the discount percentage you get will depend on the number of people signing up for this year’s promotion, but even if only 1 person signs up (you) you will immediately get a 12% discount. The ranges look as follows:

Quantity Discount Cost
1-199 12% $176
200-299 14% $172
300+ 15% $170

If more than 1000 people sign up, VMUG HQ will also do a raffle and give away some cool VMUG Advantage “swag”. Can’t wait? Sign up for the discount code here, and join the program! Note, the survey is open for 2 weeks, so from the 19th of April 2023 until the 3rd of May, after the survey closes the discount code will be distributed to all those who signed up.

UPDATE: The goal has been reached, and you can get a 15% discount when using the code: ADV15OFF. Note: This promotion is only available until May 3rd, 2023!

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About the Author

Duncan Epping is a Chief Technologist in the Office of the CTO in the Cloud Infrastructure Business Group (CIBG) at VMware. Besides writing on Yellow-Bricks, Duncan co-authors the vSAN Deep Dive book series and the vSphere Clustering Deep Dive book series. Duncan also co-hosts the Unexplored Territory Podcast.

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