We do our research and testing within the confines of a test network.
Sometimes it's a single Windows forest with a single domain and
sometimes it's a multi-domain, multi-forest, multi-OS monster. Mostly
it's not meant to exist for more than a few months, so I don't spend a
lot of time worrying about keeping it viable in the face of natural
disaster or even simple hard drive failure. If something in the test
Windows network dies, it's not going to mean its not going to put me
out of business. Can you say the same?
Do you have a disaster recovery plan for your Windows network? I'm not
talking about simple data or even system backup here. I'm talking about
your plan for completely recovering from the loss of your Active
Directory infrastructure. Could you withstand the loss of one of your
operations masters? How about the first domain controller installed in
a domain? How long would it take to rebuild the DC? Would that time
span be short enough to prevent you from major revenue loss?
There are two themes here: First, you should have a comprehensive plan
for recovering from the loss of any part of, or all of, your AD
infrastructure. Second, you should be able to do so without causing
your business financial ruin.
First things first. What should you be doing today that might save your
hide tomorrow? Here are three important steps: if you aren't doing
them, you should be asking yourself why.
1. Back up every DC, but make doubly sure you back up every operations
role master, global catalog server and the first DC in the domain. You
can only restore a DC from its own backup. You can create new DCs in
the domain to take the place of those that serve no special role, and
you can recover operation masters and rebuild a GC, but can you do so
fast enough?
2. Back up frequently. A backup older than the tombstone age set in AD
is not a backup. A tombstone represents a deleted item. The tombstone
exists so that an item can be replicated throughout AD, making sure
that each DC eventually has deleted the item. If your backup is older
than the tombstone age, you won't be able to successfully use it to
restore a healthy AD back to your pre-disaster state.
3. Practice recovery of each type of DC loss. If you don't have a test
network to attempt this on, get one. It's a small investment that can
mean everything.
There's a lot more to disaster recovery -- and, more importantly,
maintaining business continuity.
