vSan host question

[CorvetteFan]

Hello,

I have a 5 host ESX cluster running ESXi 6.5 update 3.  2 of the hosts were former vSan Nodes and have local storage.  Question is, I'd like to enable them for vSan to make use of the storage.  Can all 5 hosts reside in the same cluster?  I read the following statement from a VMWare Document.

"A host with no local storage can be added to a vSAN cluster. Note that all hosts in a vSAN cluster require vSAN licensing to use the vSAN datastore regardless of whether they contribute storage to the vSAN datastore."

I'm only looking to license for vSan the 2 hosts that have the local storage.  If the vSan storage is only aviable on those 2 hosts, I'm fine with that. 

Thanks,

[Alex_Romeo]

Hi,

It's Possible.

https://www.virten.net/vmware/vmware-vsphere-esx-and-vcenter-configuration-maximums/

https://www.wojcieh.net/vsan-configuration-maximums/

Alessandro Romeo

[TheBobkin]

"It's Possible."

Alessandro, that is incorrect information and I also have no idea why you posted images and links to completely unrelated information.

CorvetteFan, this isn't going to be possible in any supported manner for the following reasons:

1. Yes, adequate vSAN licensing is required for ALL hosts in the a vSAN-enabled cluster regardless of whether they have vSAN-storage configured.

2. 3 nodes with configured storage is the minimum required unless you wanted to go with something very unorthodox like a 3+2+1/2+3+1 Stretched cluster (requires Enterprise vSAN licensing) with one node with vSAN-storage per site (and then again you would still require a 3rd site for running the Witness) - you also couldn't configure a 2+1 Direct-connect with other compute-only nodes also in the cluster as this requires the vSphere cluster to have precisely 2 members from the start.

Is there a reason why you don't just put these hosts in their own 2+1 or 1+1+1 cluster and maybe run the Witness on one of the remaining nodes (in their own non-vSAN cluster)?

Bob

[CorvetteFan]

Thank you for the reply.  The reason is compute.  Resources are very tight here.  Having 2 clusters will not allow for enough capacity for a host failure and the shared storage is at its limit.  New hardware is on the way, but it this is an immediate need. 

[TheBobkin]

I can't say for 6.5 U3 as I don't have a cluster configured with this on hand (from home) but in 6.7 (GA) there actually isn't a guard-rail preventing from adding additional nodes to a 2-node cluster e.g. it will prevent from initially configuring it if more than 2 nodes in the cluster but it doesn't prevent adding nodes after (and IMO it should, so I will be following up on this) - this isn't a supported configuration so all onus is on you if anything goes wrong, but in theory you could configure a 2+1 cluster (DO NOT run the Witness VM on the cluster), and add the other nodes as compute-only after (or just a supported Stretched-cluster configuration but this requires Enterprise licensing). You would still require vSAN licenses for the compute-only nodes but if this is a temporary arrangement and you have valid Evaluation licenses this would suffice.

While I understand what "immediate need" can mean, I wouldn't advise janking together a cluster on the fly to meet these needs - there are almost always other approaches that can be taken e.g. validating that 100% of what is running/stored on the cluster(s) is actually required/not bloated/not running on snapshots/not over-provisioned (storage and compute) etc. - unless you know your environment extremely intimately you would be shocked at how much bloat there can potentially be.

Bob

[Alex_Romeo]

HI TheBobki.

I probably misunderstood the question.

Writes "Can all 5 hosts reside in the same cluster?" but then specifies that all the licenses are needed, I considered it as an answer.

Then he writes "I'm only looking to license for vSan the 2 hosts that have the local storage"... and my answer refers to the latter.

There are no problems for two who are licensed.

Sorry!

Alessandro Romeo