What is a Config VVol Anyways?

I have blogged a decent amount recently about VVols and in many of those posts I mention config VVols. When using vSphere Virtual Volumes, VMs have one, some, or all of the following VVols types:

  • Data VVols–every virtual disk you add creates a data VVol on your array
  • Swap VVol–when you power on a VVol-based VM, a swap VVol is created. When you power it off, this is deleted.
  • Memory VVol–When you create a snapshot and store the memory state or when you suspend a VM, this is created.
  • Config VVol–represents a folder on a VVol datastore.

This statement about config VVols deserves a bit more attention I think. What does that really mean? Understanding config VVols is important  when it comes to recovery etc. So let’s dig into this.

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VVol Lightboard Videos

Quick post. I did some light board videos together on vSphere Virtual Volumes. Lightboard videos are pretty fun to do, the unfortunate part is that I have horrible hand writing. So I immediately apologize for that.

A common question I get with these videos is how do you write backwards. I don’t. I am nowhere near that skilled, as you can see I can barely write forwards. I write normally which appears backwards and the video team mirrors the video.

This is a three part series, the entire playlist can be found here:

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Moving from an RDM to a VVol

Migrating VMDKs or virtual mode RDMs to VVols is easy: Storage vMotion. No downtime, no pre-creating of volumes. Simple and fast. But physical mode RDMs are a bit different.

As we all begrudgingly admit there are still more than a few Raw Device Mappings out there in VMware environments. Two primary use cases:

  • Microsoft Clustering. Virtual disks can only be used for Failover Clustering if all of the VMs are on the same ESXi hosts which feels a bit like defeating the purpose. So most opt for RDMs so they can split the VMs up.
  • Physical to virtual. Sharing copies of data between physical and virtual or some other hypervisor is the most common reason I see these days. Mostly around database dev/test scenarios. The concept of a VMDK can keep your data from being easily shared, so RDMs provide a workaround.

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Do thin VVols perform better than thin VMDKs?

Yes. Any questions?

Ahem, I suppose I will prove it out. The real answer is, well maybe. Depends on the array.

So debates have raged on for quite some time around performance of virtual disk types and while the difference has diminished drastically over the years, eagerzeroedthick has always out-performed thin. And therefore many users opted to not use thin virtual disks because of it.

So first off, why the difference?

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