Getting started with VCF Part 11 – External Storage

I got an interesting question recently on my VMware Cloud Foundation (VCF) blog series. An observation was made that all of my posts highlighted vSAN as the storage for both the management domain and the workload domains. The question was whether other types of storage could be used in VCF. While we would always promote vSAN as the primary storage for VCF, the answer is yes, other storage types can be used. But I need to qualify this statement. The management domain always uses vSAN. This is automatically configured during the bring up process of the management domain and provides persistent storage for management components such as SDDC Manager, vCenter servers, NSX Manager nodes, vRealize Operations Manager, vRealize Log Insight and vRealize Automation. However, workload domains can also be deployed with other storage types, such as NFS or VMFS formatted LUNs presented to the ESXi hosts via fibre channel.

When creating a workload domain (WLD), a number of hosts are commissioned and then added to the WLD during the deployment. For details on how to commission a host, part 5 of my VCF blog series explains the steps. The actual creation of the WLD is covered in part 6. Since I have already covered these steps in detail, I won’t repeat the whole sequence here, but rather cover the steps that are different when VMFS formatted LUNs presented over fibre channel is the preferred storage for a WLD.

Step 1. Format a shared LUN with VMFS

In my example, I am going to add 3 newly commissioned hosts to my new WLD. These hosts have access to a shared LUN from an external fibre channel storage array. This LUN needs to be formatted with VMFS before it can be used as storage in the WLD. This is very simple to do – simply log onto to one of the ESXi hosts and format the LUN with VMFS from there. Since this LUN (now datastore) is shared on all hosts, a simple rescan will show the LUN as a formatted VMFS volume on each of the commissioned hosts, as shown below.

Step 2. Commission hosts with VMFS on FC

We now commission the hosts. This time, as the hosts are added for validation, we specify that the storage type as VMFS on FC. In the previous host commission in part 5, we specified vSAN. Note that a big difference is that we did not have to format the vSAN datastore in that earlier example – it is taken care of automatically. However for VMFS on SC, we do need to format the datastore manually before it can be consumed.

Complete the commissioning. Assuming the validation succeed, we can now proceed to building the new WLD. If there are issue with the validation, look back on part 5 to see how you can troubleshoot and resolve potential validation issues.

Step 3. Create a new VI Workload Domain

Many of the steps involved in creating a new VI WLD will be identical to the last time we created a workload domain, detailed in part 6. However on that occasion, when asked to make a Storage Selection for the WLD, we chose vSAN as the storage type. This time, we are going to choose VMFS on FC (fibre channel) as shown in the Storage Selection window below..

Now we move onto the creation of the VI workload domain in earnest. Everything is much the same as what we saw in part 6. When we get to the Storage section, we must now provide the name of the VMFS datastore that we manually formatted earlier. In this case I have imaginatively called it vmfs-datastore.

And that is basically it. Complete the VI configuration, review and finish. All going well, your new WLD should now be active, and your new VMFS on FC Storage details should be visible.

So while vSAN is a still a requirement for the VMware Cloud Foundation management domain, vSAN, VMFS and NFS are available as external storage for the workload domains.

10 Replies to “Getting started with VCF Part 11 – External Storage”

  1. Hey Cormac, nice blog again. Did you find out if it is possible to add NFS or SAN to the Management-WLD at a later stage on a separate Cluster? Like building first Cluster with vSAN and additional ones with NFS/SAN?

    1. The only thing I tried was to add NFS to existing ESXi hosts in the MGMT cluster – that worked absolutely fine, and the NFS storage also showed up automatically in the SDDC Manager views without me having to do anything else.

      I haven’t tried creating new clusters with different storage though – is that a use case you have?

    1. Here is the deal Matthieu:

      VxRail =
      vSAN only as Primary Storage for mgmt domain.
      vSAN only as Primary Storage for WLDs.
      FC/NFS supported as secondary storage.

      vSAN Ready Nodes =
      vSAN only as Primary Storage for mgmt domain.
      vSAN/FC/NFS supported as primary storage for WLDs.
      FC/NFS supported as secondary storage.

  2. Hi Cormac, what is the minimum number of nodes for a external storage workload domain?

    1. Everything I’ve read on VCF has always stipulated that you need a minimum of 3 hosts for the WLD. I don’t think the type of storage matters.

  3. Cormac is it possible to change the DNS used when commissioning new hosts? I need to replace the IP without attempting to change it on my existing management domain. Is there a file I can update on the OS as, well, a hack?

    1. I honestly do not know Drew. Can you open a service request with support? If there is a way to do it, they will know.

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