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The situation is like this.

The customer has 2 physical servers running 1 ESXi each, running virtual DHCP and DNS windows server on both ESXi as redundancy,he wants to add a 3rd server, and have vCSA with vSAN configured.

I have thought of 3 ways to go about it.

  1. To implement it such that vCSA is installed at the DC (NOT as a separate physical server), ESXi installed on 3 physical servers on-site, with vSAN. Here my question is where will the witness be ?

  2. Physical server as vCSA running on ESXi, same server to run as witness, and the remaining 2 servers with 1 ESXi each, is this a good approach. The vCSA server will be in the data center connected over WAN.

  3. Another way is to have 4 physical servers, 2 servers with ESXi, and the 4th server with ESXi running vCSA and is used for vSAN configuration, 1 server as witness, all on-site.

Thank You

Network design PDF file

Any thoughts.

Thank You

Huud Rych
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1 Answers1

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Old article, but something to think about when implementing vSAN: http://www.yellow-bricks.com/2013/10/24/4-minimum-number-hosts-vsan-ask/

With three hosts you should theoretically be fine unless something happens to one of the remaining hosts while you’ve got one machine down for maintenance. This issue can be mitigated by not only evacuating VMs but also evacuating all their data when putting a host in maintenance mode. Note that this extends the time required for entering maintenance mode considerably.

To be honest I would probably just run VCSA inside such a virtual environment, but I would make sure to have some kind of non-vSAN storage available - perhaps something as simple as an NFS NAS - as an added security to simplify recovery in case of disaster.

Mikael H
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  • Thanks, I believe the link is for a 3 node setup wherein there are 2 ESXi hosts and 1 Witness, I have 3 ESXi hosts plus 1 Witness, unsure it would be the same interms of implementation.. – Huud Rych Mar 03 '19 at 16:19
  • With three hosts you don't need a separate witness, with the caveat I mentioned in my post: vSAN will create data redundancy across all hosts in such a way that you (temporarily) will survive a host or disk failure. Four hosts is the smallest size vSAN that will automatically self-heal after a failure, but three hosts is the minimum to run without a separate witness. In fact I'm unsure if you can even set up a three-host vSAN with a separate witness appliance. – Mikael H Mar 03 '19 at 16:41