Or, more accurately, my back-up.
I've been startled over the course of this year so far to see the number of fellow creative professionals who've reported disruption to their schedules, or the loss of their work, due to hardware failure or data loss. Now, admittedly, before my life in comics I spent several years as a production manager, meaning that a non-trivial fraction of every working day was spent worry about contingency plans, but if you do any work of value on your computer, from paid freelance to work to cataloguing family photos to saving your favourite recipies, then, forgive my bluntness, but this is the best advice anyone is going to give you today:
Back your shit up.
(I'm going to talk about Macs, because I own Macs, and I know Macs. If anyone wants to chip in Windows/Linux back-up solutions in the comments, please feel free.)
If you own a Mac, you already have a head start, because you have Time Machine. It's built-in, it's designed to be a back-up solution for people that don't use back-up solutions and people still don't use it! External USB hard drives are cheap. Buy one that's at least the same size as your internal drive; plug it in; your Mac will actually ask you if you want to use it for Time Machine. Click "yes" and you're done. Your Mac will now invisibly back itself up every hour until the drive is full, and then it will ask you if you want to a) switch to a bigger drive, or b) start deleting the oldest back-ups.
Time Machine is Level One of my back-up strategy. The external Time Machine drive is twice the size of my Mac's internal drive, so it keeps back-ups of my entire drive going back a decent length of time. I use it less for protection against data loss than almost as a versioning tool, and insurance against accidentally deleting or overwriting files. Meant to go "Save As" to create a new version of your file, but hit "Save" instead? No problem. Do your "Save As" and then use Time Machine to retrieve the old version of the file you've just over-written. Deleted a file only to discover that you actually still needed it? No problem, assuming that it was on your system for over an hour, Time Machine still has it.
If you own a Mac, enable Time Machine. Do it. You have no excuse. Short of USB ports? No problem — Apple sells the Time Capsule, which doesn't even need to be attached to your machine. Your Mac will back itself up over wifi.
Time Machine is great (as an aside, you can also use it migrate the entire contents of your computer* to a new Mac painlessly) but it has one key problem: it doesn't create a bootable back-up.
If your Mac's internal drive fails and your machine won't boot, you can't start it up from a Time Machine back-up. If you hold down ALT (Option) at start-up, your Mac will look for alternative drives from which to boot. If the normal boot drive has failed, it will automatically look for another drive for start-up, and your Time Machine back-up ain't it.
Which is why I have a second external drive hooked up to my machine. This one is a portable drive the same size as the internal. There are lots of third-party back-up solutions, but I use Carbon Copy Cloner.
Because you can schedule CCC back-ups, and you can schedule your Mac's start-up time, my machine auto-boots at 6:00am and at 6:15, CCC makes a bootable clone copy of the hard drive, which takes about 20 minutes. By the time I sit down at my computer in the morning, the entire drive has been backed up, meaning that, in the event of a complete drive failure, I can boot from the clone and, at worst, I will have lost whatever work I've done that current day, since the CCC back-up. If you have the luxury of a lunch break, or time when you're reliably going to be away from your machine, you could set CCC to do one or more back-ups during the day.
(This is not to say you can't work while CCC is running — you can, but the machine slows down noticeably, and the back-up takes longer, so there's a trade-off.)
Archiving. Particularly if you're doing a full-time job, internal drives fill up rapidly, so it's sensible to have a third drive for archiving off old jobs. Fairly recently, I realised that this drive wasn't getting backed up by Time Machine. Now, I could add the archive to the Time Machine preferences, but this is largely static data, so backing it up hourly seems like overkill. I used to keep a rolling system of backing up to DVD, but optical media isn't always as reliable as people like to think, and the process was time-consuming and required extra record-keeping to maintain an index of what projected were archived to which disks.
So I bought a 4TB RAID1 drive. It's actually two standard 4TB drives in a single box. In a RAID0 configuration (these sound complicated, but it's literally a tick box to configure in the software) both drives are used to write data and the drive appears as a single 8TB drive.
I have no idea why anyone uses RAID0. You have no data redundancy in this configuration and if either drive fails, all your data is gone. In RAID1 configuration (the default it ships with), identical data is written to both drives simultaneously, so it appears as a single 4TB drive on your desktop.
In the even of a drive failing, I can simply order a replacement, carry on working from the still-working drive, and replace the failed one when the new drive arrives. Yes, it's possible that both drives might fail simultaneously, but we're entering mathematically improbable levels akin to my house being totalled by a falling jet airliner. Possible, but not really worth losing sleep over.
(There are higher RAID configurations, but RAID2, 3, 4, etc, simply describe more complex configurations of larger numbers of drives.)
I haven't yet implemented Level Four, but I'm mindful that I'm still vulnerable to, say, burglary or a house fire, so I'm currently investigating off-site back-up options like CrashPlan. Services like Dropbox might look like an option for off-site back-up, but I don't think they guarantee the integrity of your data, and I'd like something a little more solid. I'll update this article when I've made some progress with this.
For most people, you don't need to go further than Level One, or Level Two, but take a moment to stop and think about what's on your computer.
Now think about how you'd feel if it was all gone. Think about how much it would cost you to recreate lost work. Think about what can't be replaced at all: family photos, correspondence… yes, some of this might be recoverable if you kept it in some Cloud services, but you're entirely reliant on someone else to look after what's precious to you.
Data storage is cheap. Backing up is easy.
Back your shit up.
*Except Adobe CS products, which can't be migrated. You have to de-authorise your current Mac, run a Time Machine back-up, plug the Time Machine drive into your new Mac, restore everything except your CS applications, then install your CS apps fresh from the original installers. Thanks a bunch, Adobe.