Backup: things you should know

Backup is a vital part of your IT life: without it you are risking a world of pain. We know, because we are in at the bitter end. So, what should you know?

First things first. You should always "plan for the worst, hope for the best" - not the other way round. So, we're always looking at "worst case" - normally total loss of the system. And the way you should deal with that depends on who you are, and what you're trying to protect. And you must remember, responsibility for protecting your data is down to you, and you alone. We can advise, maybe even recommend - but it will always be your responsibility to actually manage and protect your data. Finally there are some scary statistics concerning the survival rates of companies that suffer major data loss. Ignore this at your peril.

Let's start simple. You have a laptop. On which are some photos, some documents and a couple of other bits & bobs. Backup is easy - plug in an external data store (USB stick's aren't ideal, but they'll do at a pinch), copy your "My Documents" folder etc. and put the device in a safe place. Now let's imagine it gets stolen. Leaving aside the implications of all that data being in a criminal's hands (which we will cover in another post), recovery is pretty simple. You buy another laptop, plug in the device, copy the stuff back, and you're done. Problems? Several, but all easily overcome. The USB stick was in the same bag as the laptop that got stolen. You didn't actually get round to backing up that last set of photos. The USB device goes faulty on the very day you need it. Obvious problems with obvious fixes.

Moving up a step. You have a system that has a lot of software installed on it, as well as the associated data. In the event of a system loss you can follow the route above: replace the box, recover the data and re-install the software. But this will be very time consuming. Plus there's the problem of finding all the install discs, finding the license keys, and re-doing all your settings & calibration. Then waiting for it all to update. It's a process that can take hours - even days - to complete. The solution to this is to "image" the system. This is a complete snapshot of the system at the time the backup is taken. In the event of a recovery being needed, the system can be restored to that exact state, although any data changed in the period between the last backup and the failure will be lost forever. Although subject to the potential problems listed above, and not a trivial matter, this is all pretty straight-forward. However, there is one major problem. The recovery has to be done on replacement hardware that is pretty near identical to the original - otherwise it just won't work. While this is a not problem if we're talking about a new(ish) laptop, an older or more complex system could prove more tricky.

Virtualisation is a technology with many uses, including backup. It's advantage is that the virtualisation program (the hypervisor) isolates the system from the actual hardware, acting as an impartial broker. Now, if your failed system was backed-up as a VM (Virtual Machine), you can drop the VM image onto any suitable hypervisor and off you go. It's a worthwhile option to consider, especially on servers, where the rebuild & reconfiguration times can be measured in weeks. It's still not a trivial process, and the backup is only as good as your routine to keep it refreshed, but it is a very good solution.

Real-time backup & hybridisation takes this one step further. Normally done in conjunction with a dedicated device in the network, these systems maintain near-real-time backups of the protected systems as VMs. If you need to perform a recovery, your systems can be started as VMs on the device without the need to replace the failed hardware. You can be back to a level of functionality within minutes. The hybrid systems go a step further, and synchronise with "the cloud" adding a robust off-site element to the mix. With these systems you can virtualise your whole IT infrastructure as a backup in the cloud, enabling you to continue even if you loose your entire office...

Just a final note of caution. These are only words: a backup strategy can only be considered fit-for-purpose if you have tested it. It's no good at all if you need to recover your system for real, only to find there is some unexpected problem that prevents it happening.