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. We'll go into a number of them here and how they affect a new desktop build.
RAID 0 Plus a Spare Disk RAID 0 is the preferred hard disk solution for gamers or people that need the fastest disk access. Large files over a certain size - called the stripe size - are broken into "stripes" and the stripes are written to alternate disks. Generally, the number of hard disks in a RAID 0 array is two, but it can be more. If it is two, the first stripe-sized block of a file is written to one disk and the second stripe is written to the other disk. The stripes can be fed to the two disks in parallel nearly doubling both their read and write speed.
The first and major plus as mentioned is the greatly improved write and read speed. Also on the plus side, no disk space is lost in RAID 0. Two 500GB drives would appear as a single 1TB. On RAID 0's minus side, if either disk fails, all files over the stripe size are lost since half of a file (assuming a two disk raid) is little better than no file. One way to resolve this problem is to have a third non-RAID disk of the size of the RAID 0 (or larger). This drive will be used to contain one or more more backups of the RAID 0 array. Some form of backup software such as Acronis True Image Home 2010 would then be installed and configured to perform backups on a regular - typically nightly - basis. Note that the latest version of the product has "Acronis Nonstop Backup™ [that] automatically creates incremental backups every five minutes allowing users to roll back their system, files, and folders to any point in time in the past." While this sounds good, it may well defeat the purpose of a RAID 0 drive or at least reduce it. There would need to be some sort of synchronization or checking of the backup in real time that would slow down the RAID array. Since it's incremental, it may not be much in reality. Acronis also has a powerful scheduler to make the backup at some time when you are not on the computer. This would not interfere with the computer while it's in use, but the risk is loosing any data created since the last backup is run.
From a build point of view, again we need is a motherboard that supports RAID or we need to buy a RAID controller add-in card. The second thing we need is a matched pair of disks and a third disk that's approximately the size of the RAID array. As before, the disks to be used in the array don't have to be the same, but it's more efficient that they are. If a 320 GB drive is paired with a 500GB drive, the resulting RAID 0 array will be twice the size of the 320GB drive or 740GB with the extra space on the 500GB drive wasted. If the two drives have a significantly different write times, the effective write time is that of the slower drive. This would waste the potential speed of the (presumably more expensive) faster drive.
Assuming that the backups are being done on a schedule rather than continuously, the third drive could also be an external USB or ESATA drive. The ESATA drive would be preferred due to the significantly increased speed over USB. This would allow buying a (very large) external drive to be shared among systems. A pair of external drives could be used with one of the two being kept at another physical (called "offsite") location. In the event of theft or fire, some version of the data would be safely elsewhere. Online backup solutions such as Carbonite and Acronis Online Backup can also be used for this if you have a good upload speed to the Internet from your computer. The third "drive" could also be a folder on another computer on your local network or a networked attached storage (NAS) device. Those solutions aren't discussed here.
Disks are installed using the same rules of thumb as with RAID 1. Leave airspace between the drives if possible and use or install fans for the drive cage, if possible. The power and data cables should be kept out of the way if possible. The picture below shows a pair of drives used for RAID 0 and a third, larger drive used for backup. (The case is an Antec Nine Hundred.)
As before, rather than giving instructions for setting up a RAID system here, please refer to the list of guides found on the Internet such as those listed in the first section.
RAID 0+1 Regarding the RAID 0 discussion above, it would be ideal to having continuous backup that somehow doesn't inhibit the RAID 0 speed writing the backup data to a non-RAID disk. If we had a second, identical RAID 0 array, it could be used as the backup of the first using Acronis or some other software. This is the core of the solution provided by RAID 0+1, which is also known as RAID 1+0 or RAID 10. Essentially a pair of RAID 0 arrays is used in a RAID 1 array. This gives us (nearly) the speed of a RAID 0 array with the data redundancy and security of a RAID 1 array. Generally, the number of hard disks in a RAID 0+1 array is four.
The first and major plus of RAID 0+1, which was already mentioned, is the combination of the advantages of RAID 0 speed and RAID 1 security. If any single disk fails, no data is lost. The failed disk can be replaced and the RAID rebuilt from the remaining disks. RAID 0+1's first minus side is the same as RAID 1's side: only half the disk space invested in the RAID array is seen as usable disk space. Four 500GB disks would appear as a 1TB RAID as opposed to 2TB in RAID 0. A second negative aspect of RAID 0+1 is that while it is considerably faster than RAID 1 while providing RAID 1 security/redundancy, it is slower than RAID 0 alone.
From a build point of view and as before, we need is a motherboard that supports RAID or we need to buy a RAID controller add-in card. This time, however we need a set of four matched disks. The same caveats about disk size and speed apply as in RAID 0 and RAID 1. One additional factor in the mix is that you need a case that can have four internal hard disks and still have decent air flow. Leave airspace between the drives if possible and use or install fans for the drive cage, if possible. The power and data cables should be kept out of the way. The picture below shows four drives in RAID 0+1
As before, rather than giving instructions for setting up a RAID system here, please refer to the list of guides found on the Internet such as those listed in the first section.