Here we'll formally consider Storage Spaces Direct, or S2D for short.
Storage Spaces Direct is a software‑defined storage solution that is
meant to help businesses who may not have the resources or
hardware‑based storage area network appliances.
These would be storage subsystems that are network‑connected
normally accessible via the iSCSI protocol.
Maybe if you can afford it,
there's the Fibre Channel hardware that gives you that shared
storage layer that a failover cluster requires.
But,
Storage Spaces Direct instead allows you to combine
between 2 and 16 Windows Server cluster nodes that will
share their own commodity storage, that is,
their internal and/or direct‑attached storage,
without that need or dependency on dedicated SAN hardware.
So is Storage Spaces Direct something every customer will want?
No, absolutely not.
If your business is big enough, and you're failover cluster
needs and your needs for redundancy and speed are such that
you can afford SAN hardware, that's totally cool.
But at the very least,
you need to know how to use Storage Spaces Direct for the exam.
Because we have to remember that this is a vendor‑proprietary certification,
and so Microsoft isn't going to ask you about third‑party OEMs,
or original equipment manufacturers.
Now Storage Spaces Direct is cool because it's free.
It's with Windows Server license, so it's free with a license.
It's also something you can do for both physical and guest failover
clusters, now this is important. That last piece about guest
failover clusters is important for you as a certification candidate
because I've mentioned this before,
you should have a test lab where you can work with
this stuff all on your workstation.
If you have, say, a laptop or a desktop running Windows client,
when you have an appreciable amount of RAM,
I would say 32 GB would be awesome, you probably could squeak by with 16,
but I would hope as a baseline you have 32,
and as long as your client workstation is running an appropriate
stockkeeping unit of Windows 10 or Windows 11,
it's basically Professional, Enterprise,
or Education,
you can install Hyper‑V Server on the client and download
evaluation editions of Windows Server,
and you can get going with failover clustering. And
that's not exactly a guest cluster.
A guest cluster, though,
would be where you have a virtual machine on which
you enable nested virtualization, and you set up the VM as a cluster node,
which is totally fine and totally supported.
Now, Storage Spaces Direct is intended for dual‑storage layer infrastructures,
in other words, tiered storage.
The best cases for Storage Spaces Direct is where each of your cluster nodes,
your server nodes, has a mixture of solid state and lower‑speed HDD disks.
This is great because then Storage Spaces Direct can use high‑speed
caching with the SSD drives, and also you can prioritize data that's
particularly volatile on that high‑speed storage.
Microsoft doesn't officially support all HDD
deployments in Storage Spaces Direct, even though you can physically do in all HDD SD2 deployments.