I get this question a lot. And when I say a lot, I mean a LOT.
I don’t work at VMware anymore, and I can’t speak for officially for VMware or vSAN, and I can’t reference anything beyond what’s in publicly available docs, but having worked on the product for 5 years, I’ve got a lot of information and insight into it. I had a great time growing at VMware and thoroughly enjoyed working on the vSAN product. With that, I’m having as much fun and more at Pure Storage working on all the things VMware that we integrate and intersect with.
But this post isn’t about me, it’s about vSAN and additional storage.
vSAN and External Storage
Let’s start with the $64M vSAN question is “Can it be used with Traditional or vVols Storage?”
In the summer of 2018, I wrote a blog post about just this topic while I worked at VMware.
Understanding vSAN -Can it be used with Traditional or vVols Storage?
I wrote this post to highlight use cases where a customer might find it desirable to have both vSAN and external (vmfs/nfs/vVols) storage.
Use cases such as:
- Continuing to be able to use existing storage investments that are still supported
- Migrating from a soon to be retired legacy storage platform
- Using a combination of vSAN and vVols
- and more…
Another use case I would add here is when a vSAN customer might want to add additional external storage for specific use cases that could be based on performance, capacity, or even data services.
Storage Policy Based Management
When VMware introduced storage policies, I immediately saw where they could be used to help determine VM workload placement.
When vSAN came out, storage policies were used as the core mechanism to assign protection, performance, and capacity assignments to a VM workload. And let’s not forget that vVols, like vSAN, use storage policies to capitalize on SAN or NAS capabilities.
With Storage Policy Based Management as the common component across SAN/NAS/vSAN storage, a virtualization administrator can easily place workloads on storage that meets the workload or use case requirements.
So Does External Storage Integrate with vSAN?
To kind of summarize Cody’s post, he covers vSAN, storage policies, and the fact that those vSAN policies expose the capabilities of vSAN. Which is great, and external storage does that too!
External storage arrays have many of the same features as vSAN baked in or automatically/pre-selected, so it really isn’t necessary to support running vSAN on external storage. The gap in the past is that virtualization administrators haven’t really had an easy way to see those capabilities and capitalize on them at a per-VM level. Sure datastores can be tagged, and a tag policy can be used, but it isn’t the same as vSAN.
vSAN gives the virtualization admin the ability to apply policies on a per-VM or per-vmdk level. With VMware Virtual Volumes (vVols), just like vSAN, storage policies can expose the native capabilities of external storage at a per-VM or per-vmdk level.
Does external storage integrate with vSAN? Not really, but it can absolutely complement a vSAN environment.
If you’re comfortable with provisioning based on policy using SPBM, vSAN can be used right along side traditional (using tags) and vVol based storage.
What about vendor support?
This is where it can also get confusing. Does vSAN support using <insert vendor here> external storage? Well, vSAN isn’t going to support external storage. But VMware vSphere WILL, as long as it is on the VMware Hardware Compatibility List.
So VMware will support external storage on a vSAN Cluster? Yes, provided that external storage is on the HCL.
A customer asked me recently “Well we have vSAN with VxRail. Can we still use external storage with VxRail?” – Yes!
Dell even calls attention to this on their site, and that VxRail SUPPORTS external storage (even Fibre Channel): https://infohub.delltechnologies.com/l/techbook-dell-emc-vxrail-system-2/external-storage-8
Adding an external storage system to VxRail isn’t going to integrate with VxRail management, and isn’t going to be supported by Dell, but would still be supported by VMware from a vSphere standpoint.
|Supported Stack Components|
|VMware||Dell||External Storage Vendor|
|“vanilla” vSAN||vSphere, vSAN, External Storage (based on HCL)||Compute nodes, vSphere, vSAN, Dell Storage||External Storage|
|VxRail||VxRail & External Storage (based on HCL)||VxRail & External Dell Storage||External Storage|
In short VMware vSAN (‘vanilla’ or with VxRail) can absolutely be complemented by external storage.
Customers who wish to streamline their provisioning and management of VMs with vSAN and external storage should look deeper into using SPBM as a comprehensive provisioning and management strategy.