7. Internal / External
We call an external hard disk an hard disk who stay outside the computer. This kind of hard disk is inside a container and connected to the computer with a FireWire or USB interface. This is really practical to move data.
An other possibility is an eSata interface who start to be available with the last computer and laptop, but not on all the computers. This the external version of the SATA format.
If you choose an external hard disk in USB, take care to the supported USB version of your computer. Indeed, the USB 1.0 is really slow to make data transfer. If you don’t have USB 2.0 in your computer, don’t buy an USB hard disk. Otherwise choose an hard disk with USB 2.0 or 3.0 if you have a really recent computer. Normally the USB 3.0 hard disk are compatible with older standard.
The SSD (Solid State Drive) is a recent technology but that grows quickly. This is a hard disk but without any mechanic element. The transfer rates are better, the time to start the device is almost null and the device make no noise. Moreover the power consumption is lower and the crashworthiness is also better.
Nevertheless, the SSD have a limited life duration. Indeed, the memory cells supports only a maximal number of write cycles. This tend to be improved. By example Intel has announced a life duration of 5 years for his SSD X25-M.
But, the price is really more expensive than the price of a tranditional hard disk, 10 to 15 times more if we take the price per Go. En plus de cela, le prix est bien plus élevé que pour un disque dur traditionnel, environ 10 à 15 fois plus en prenant le prix au Go.
If you want to try SSD, this can really improve the start time of your computer and of your applications. So it’s interesting to opt for a little SSD for the operating system (32 or 64 Go). But it’s not reasonable to use a SSD to store data.
In conclusion, although the capacity is really important, this is not the only criteria. You have to keep in mind the performances of the hard disk (memory cache, rotation speed, interface) to not decrease performances of your computer.
Be also careful of the constructor and the series of the hard disk. It’s a good thing to buy a more expensive one of a good construtor instead of a noname hard disk with several problems. Indeed, some series have problems and don’t keep their promises at the level of the transfer rate. To know if a hard disk has a good reputation, the best thing is to consult comments of buyers in the sell website.