In front of a number of media, photos and digital memories more increasingly important, it begs the question of how to protect its computer data over time. In computer science, as everywhere else, zero risk does not exist. However, we can make sure bring it closer as possible to zero. Let's look at the different methods of running backups, how to combine with each other to maximize the security of your data, and especially, what are the solutions during an accident.
A backup to the test of time, for which files?
Your computer is on two main types of files. The files of your operating system to start, whether you're at Windows, Mac or Linux, you have very many files to properly operate your computer. Subsequently, there are also files related to software you have installed on your machine. The loss of system files is boring but you can put things into perspective. Indeed, even lost, it is always possible to reinstall your system after formatting the hard disk and then reinstall your software. The main constraint of this loss is time to back up your computer environment, but no personal data is then lost. The second type of file is personal data and multimedia files. These files here are far more valuable than the previous ones, each of these files is a personal touch on your computer that only you have. Whether accounting files, text files we write or last photos and vacation video. If these files are lost, it will be final! It can be concluded that there are two types of data on your hard drive. Data from the operating system and programs that the backup is not essential because never permanently lost. And files of types personal documents and personal media files like photos, where the backup is essential not to lose them after a crash of hard disk for example.
The media
For the home, there are several more or less automatic and more or less expensive backup possibilities.
External hard drives
They are removable and transportable, they are asked less often than the internal hard disk that contains the operating system of your computer and therefore less likely to be altered. It's not expensive and space-saving solution. However, only one copy of your files on a physical disk will not put your data safe in the event of a disk failure. If you have enough room I recommend retained a copy of your file on your computer and a copy on the external hard drive for the most important and irreplaceable files. See two external hard drives, one being a perfect copy of the other. Many hard drives have a management software or you can add an or even for automatic backup of data. For example, you can configure the software so that every Sunday at 15 H the drive makes an automatic backup of your data. The backup is made on a regular basis and those without needing to think about it.
The NAS
The NAS (Network Attached Storage) is similar to the external hard drive in its use. It is a box with several bays for internal hard drive. You can connect it to a box or to a router for access from all devices connect from home, it works as a server. Backing up data on the NAS is also similar to the backup on an external hard drive. It can be related to a private Cloud system because you can access your data from anywhere via the internet and a web browser to the condition of the left on. The highlight of the NAS is in the security of the data you backup. A point of purely material there is a processor, RAM and a cooling system which are studied for the proper functioning of your disks. Point of view software you can duplicate your data on several discs of completely transparent and automatic way to the user thanks to the possibilities of the NAS RAID. (See this article for more details on the different RAID systems)
CD, DVD and Blu – Ray
This method is less used as hard drives today are increasingly large and less expensive. Therefore, the CD, DVD and Blu – Ray take longer for storage, it is rather a method reserved to long-term archiving. However, beware of cheap CD/DVD can be found, some become unreadable after some years only. It is a method which takes also more space than hard drives.
Online backup
There are several rated practical storage online, as with the NAS you have access to your data from anywhere. Except that here the difference is that you "rent" material, the integrity of your data is guaranteed, infrastructure, electricity and maintenance, everything is managed by your provider. In addition it is often said that a true backup that takes into account all external risks must be done on two supports distant 300 Km (in the case of a big natural disaster or acts of war, for example). Therefore a backup at home and one on remote servers protects you for more extreme and fortunately many accidents rare pus (natural disasters, fire, burglary…) However, despite the advantages, there are also disadvantages to this method. The backup is not automatic. A site little fail, can have a punctual technical breakdown, therefore, never use only this method. Keep a copy of your data at home also.
What to do if a hard drive has failed
If one of your drives fails before we do a backup. This isn't necessarily lost. But it will be difficult to recover and be not free. If there is a problem with the data, there are paid and free data recovery software. We can quote for example the Recuva software which is free. If a hard drive fails in a system, if you replace the hard drive with a drive of the same size (of the same model preferably) you will lose any data because of the RAID. Two more complicated cases can occur. A physical failure on a hard drive or multiple hard drives that drop in a RAID System. In both cases, all the data are lost and not recoverable by the general public. In this case, companies having cleanrooms and experts to disassemble your hard drives without risk exists. For example a site offering a service of restoration of RAID data, there is Kroll Ontrack, which has many sites around the world. 
Conclusion
There are many opportunities to make backups, but each has benefits and drawbacks. The most important thing to remember is the complementarity of these methods. To make an effective backup of your important and precious data, multiply media, or even places of storage. No backup system is infallible, a NAS is protected against most of the outages, but will not survive a fire, and an online storage company is not immune to failure. Think about it for the most important data