I have used a number of backup schemes over the years. In the not-too-distant past, most of them relied on some form of redundant, automatic backup such as RAID 1 (mirroring) or RAID 0 + 1 (striping plus mirroring). However, a while back, I decided that was not good enough and moved to a scheme of using software - in my case, CrashPlan (Plus) - to back up my desktop, my laptop, and my wife's laptop to a separate PC in my house just for that purpose. Additionally, I have CrashPlan back up the same machines (and my backup machine) off-site to their servers (called CrashPlan Central). The bottom line is that it's almost a requirement to have some form of active hard drive backup, and the good news is that it's not that hard.
The following is my personal experiences with computer storage over the last 30 years or so. Sadly, the necessity of having some backup scheme for my hard disks to guard against hard drive failure increased dramatically for me in the early 2000s. Originally, I would set up a RAID 1 array fully expecting to never replace either disk. The rare occasion when I did have to replace one justified the cost in my mind. I could be quite smug when I slapped in the new replacement disk, chose to rebuild the array, and lost nothing (save the time to rebuild and the cost of the new disk). That fact was that in the early days, the majority of RAID 1 arrays that I set up would go through their entire life with no failures. I know of a couple of systems in which I included a RAID 1 array that were 4-5 years old and still running on the original drives.
Unfortunately, that changed. By 2005 or so, I set up a RAID 1 array fully expecting it to be necessary. I'm not sure what happened with the hard disk manufacturer's, but reliability just took a dive. I suppose it could be me; I'm using twice as many hard drives in the systems I build, so it follows I would see twice as many failures. I believe, however, that's not entirely the cause. As I mentioned above, my early RAID 1 arrays, for the most part, ran their entire life without any replacements. In the last few years, more than half of the RAID 1 arrays I've set up have required at least one disk replacement.
This trend doesn't seem to be limited to a particular manufacturer either. I typically use Seagate or Western Digital (WD), but I have occasionally used Samsung and IBM (now Hitachi) drives as well. I don't use the latter two often enough to include those two in the following statement: In my opinion, no hard drives can be trusted. It seems to be Seagate's opinion, too, as they first reduced their warranty from five years to three, and now that warranty is down to two years on standard models. WD has three years on most drives with their premium models at five. What that should mean to anyone with a drive older than three to five years is that it should be expected to fail at any time.
For a long, long time I was an utter Seagate fanboi; it's the only brand of hard drive I would use in builds. When I first started using RAID 1 arrays, WD had a couple of embarrassing manufacturing issues, which they initially denied and eventually acknowledged. I myself wouldn't touch the things. In 2006 or 2007, I built myself a new desktop PC with a RAID 1 array using a pair of Seagate 120GB drives. One of the drives failed fairly quickly. Because I had used so many of their drives over the years with no failures, I figured it was just my time to get a bad one and replaced the drive. Then the other drive failed within a year. Both were covered by the (then five-year) warranty, but that's not the point. Had I not used a RAID 1 (mirroring) setup, data would have been lost. I didn't feel I could trust that particular model and tried my luck with a larger 250GB Seagate. One of those failed just under two years later. Like the others, it was still in warranty, but this was not what I expected from Seagate. RAID 1 was saving the day again and again, but I really wished it wouldn't have had to.
I had a similar experience in a desktop PC I built for my daughter to take to college. One of the 250 GB Seagate drives (in RAID 1) failed after less than two years. During this same time, the company I worked for bought three WD250 GB external USB drives for a few of us working offsite to use for backing up our laptops. All three died; mine lasted the longest - almost two years. In my opinion, all hard drives should be regarded with the belief that they will fail before they are out of warranty, so having a backup is absolutely required. Sometime during all of this, I decided to use RAID 0 + 1 in my gaming desktop. That required I add another pair of Seagate 250GB drives in order to effectively get 500 GB of space. Of the four drives in use, I had three failures including one where the replacement for a failed drive also failed. I switched to using Western Digital Black drives, which had (and still have) a five-year warranty.
I now use SSDs (solid-state drives) as my main boot and file drives. Their cost is low enough to be viable replacements for HDDs (standard hard disk drives), but still high enough that doubling the number of drives needed (as used in RAID 1 mirroring) is prohibitive. I also have a pair of WD Scorpio Black drives, which have a five-year warranty. Still, I don't have enough faith in any of them not to have a complete backup elsewhere. That is where CrashPlan comes in. In the rest of this article, I'll go through the ways I have (and you can) backup your hard disks.
Hopefully, I made a convincing case above that hard drive backup is absolutely essential. It was always a good idea, but with what I'm seeing as the current state of hard drive reliability, it's no longer an option. There are lots of effective ways of maintaining a backup. In the links below, I will go into a number of them that I have used.