Yellow Bricks

by Duncan Epping

vSAN ESA supported with 10GbE networking?

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Somehow I get this question a lot lately, and it seems there’s still some conflicting documentation and messaging out there, is vSAN ESA supported with 10GbE networking or not? The answer is simple, yes it is supported officially. Although you may see some, outdated, blogs and docs state that 25GbE is the minimum, this was actually revised with the introduction of the AF-0 Ready Node configuration for vSAN ESA.

Now, I can fully understand people want this in writing, and after some digging I actually found an update documentation page on the Broadcom website that describes the vSAN ESA and vSAN OSA networking requirements. You can find it here: VMware vSAN – Physical NIC Requirements.

Do files stored on vSAN with vSAN File Services count against the max object count?

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Today I got an interesting question internally: Do files stored on vSAN with vSAN File Services count against the max object count? As I haven’t really discussed this in the past few years, I figured I would do a quick refresher. With vSAN File Services, the files people store on a file share are stored inside a vSAN object. The object itself counts towards the maximum component count you can have in a cluster, but of course the individual files do not.

When it comes to vSAN File Services, for each share you create, you will have to select a policy. The policy will be applied to the object that is created for the file share. Each object, as always, consists of one, or multiple, components. Those components will count towards the maximum number of components a vSAN cluster can have. For a vSAN ESA host the maximum number is 27k components, for vSAN OSA the maximum number of components per host is 9k. Do take into consideration that RAID-1 has a different number of components than RAID-6 for instance, but in general, this should for most customers not be a huge concern unless you have a very large environment (or a small environment and are pushing the boundaries in terms of shares etc).

I hope this helps. PS: The video below shows a demo I gave a few years back in which I inspect these components in the UI and CLI.

Doing site maintenance in a vSAN Stretched Cluster configuration

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I thought I wrote an article about this years ago, but it appears I wrote an article about doing maintenance mode with a 2-node configuration instead. As I’ve received some questions on this topic, I figured I would write a quick article that describes the concept of site maintenance. Note that in a future version of vSAN, we will have an option in the UI that helps with this, as described here.

First and foremost, you will need to validate if all data is replicated. In some cases, we see customers pinning data (VMs) to a single location without replication, and those VMs will be directly impacted if a whole site is placed in maintenance mode. Those VMs will need to be powered off, or you will need to make sure those VMs are moved to the location that remains running if they need to stay running. Do note, if you flip “Preferred / Secondary” and there are many VMs that are site local, this could lead to a huge amount of resync traffic. If those VMs need to stay running, you may also want to reconsider your decision to replicate those VMs though!

These are the steps I would take when placing a site into maintenance mode:

  1. Verify the vSAN Witness is up and running and healthy (see health checks)
  2. Check compliance of VMs that are replicated
  3. Configure DRS to “partially automated” or “Manual” instead of “Fully automated”
  4. Manually vMotion all VMs from Site X to Site Y
  5. Place each ESXi host in Site X into maintenance mode with the option “no data migration”
  6. Power Off all the ESXi hosts in Site X
  7. Enable DRS again in “fully automated” mode so that within Site Y the environment stays balanced
  8. Do whatever needs to be done in terms of maintenance
  9. Power On all the ESXi hosts in Site X
  10. Exit maintenance mode for each host

Do note, that VMs will not automatically migrate back until the resync for that given VM has been fully completed. DRS and vSAN are aware of the replication state! Additionally, if VMs are actively doing IO when hosts in Site X are going into maintenance mode, the state of data stored on hosts within Site X will differ. This concern will be resolved in the future by providing a “site maintenance” feature as discussed at the start of this article.

Unexplored Territory Episode 088 – Stretching VMware Cloud Foundation featuring Paudie O’Riordan

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The first episode of 2025 features one of my favorite colleagues, Paudie O’Riordan. Paudie works for the same team as I do, and although we’ve both roamed around a lot, somehow we always ended up either in the same team, or in very close proximity. Paudie is a storage guru, and the last years helped many customers with their VCF (or vSAN) proof of concept, and on top of that helped countless customers understand difficult failure scenarios in a stretched environment when things went south. In Episode 088 Paudie discusses the many dos and don’ts! This is an episode you need cannot miss out on!

Unexplored Territory Episode 087 – Microsoft on VMware VCF featuring Deji Akomolafe

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For the last episode of 2024, I invited Deji Akomolafe to discuss running Microsoft workloads on top of VCF. I’ve known Deji for a long time, and if anyone is passionate about VMware and Microsoft technology, it is him. Deji went over the many caveats, and best practices when it comes to running for instance SQL on top of VMware VCF (or vSphere for that matter). NUMA, CPU Scheduling, latency sensitive settings, power settings, virtual disk controllers, just some of the things you can expect in this episode. You can listen to the episode on Spotify, Apple, or via the embedded player below.