VMware VSA: The number of VMFS datastores must be 1

Today a colleague called me asking why his 5TB datastore was not showing up while configuring a new VMware VSA cluster. This post explains why, and how you should prepare for deploying VSA.

When implementing VMware VSA you should know only one datastore is allowed on the ESXi host participating in your VSA cluster and should contribute to the total amount of capacity available.

Usually, I come across hardware with a RAID1 configuration for the OS part, and a RAID5 configuration for data. ESXi is installed on the RAID1 configuration and people expect they can add the RAID5 configuration to their VSA capacity. If you want to do it right, there are two possible solutions by my opinion:

  • Make one big RAID5 logical volume of your physical disks (which, ofcourse, need to be of the same capacity) and install ESXi on this logical volume, where the remaining free capacity is automatically used to create the first datastore on this ESXi host.
  • Make one big RAID5 logical volume and install ESXi on a SD card. You end up like option 1, but keep the ESXi installation from your physical disks used for VSA storage.

So, what we did in this particular situation was creating a 5TB datastore on each ESXi host, migrating data from the RAID1 datastores to the 5TB datastores and deleting the RAID1 datastores. ESXi is not installed on the datastore, so you can safely delete the datastore when your data is off.

Now the VSA wizard doesn’t show any errors and is being enrolled as we speak.

Thanks for reading!

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