We have a number of older Dell storage servers, which would be ideal for this purpose, rather than install on virtual machines, to separate the virtual machines (backup) (VMDK) from the same datastore as the virtual machines.
Otherwise we could repurpose these storage servers, and use as a NFS datastore present to ESXi, and the storage could be used this way.
That kind of install is unsupported. I can't say it hasn't been played with, but some issues were found (I don't have details).
But if the old Dell servers will take the .iso then they should also take a basic install of CentOS 7, right? And that gives you kvm that you can do the install with for no investment.