Life and Death of Storage Devices 2: USB Flashes / Camera memory

As I’d mentioned in the first section of this series on CD-R and DVD-R, East Africa is a rough environment for storage devices. The last 3 years have seen an explosion of cheap flash devices into the computer world. This has come so far that in 2009 we can only sit and laugh at very unreliable 1MB floppies and even 100MB Zip disks that you might see at computer junk stores. Already in Tanzania 2GB flash drives are common and, at least abroad, quality 16GB flash drives are inexpensive (35000/= TSH).

Camera memory (like SD cards) and USB flash drives rely on much the same technology so I will discuss them together.

The moving parts of the mechanical hard drive cause ~90% (?) of their failures. The Flash drive has no moving parts inside. This might make you think that this means the USB Flash has no chance to break. You would be wrong though. If you are working in a windows environment with lots of viruses you’ve probably seen flash drives break more than once.

My understanding of Flash drive technology is not perfect (see Wikipedia & other references below) but it seems that there are several ways to design flash drives that make trade-offs for speed, capacity, or longevity (longer life). Ideally you want a good amount of all three. I suspect that many cheap manufacturers may use fewer, cheaper chips inside their drives to make capacity very large while hiding the shortened lifetime and speed. (A technical discussion of these are made in a part of this article on flash-based hard drives)

Longevity, or the length of the life of the flash drive is talking about the amount of times you can Write and Read anything from your drive. For quality flash drives, these numbers are generally very large: Millions or billions of times. There are even very advanced algorithms in the drives which balance out the load to reduce the damage. But on cheap flash drives or under the assault of many very kali Windows viruses for weeks after weeks you can quickly find that your flash is at the end of its days.

Viruses want to spread. The instructions that code a virus are not written carefully to help your computer, the programmer is very lazy. In East Africa most viruses specifically want to spread through your flash drive. This makes it very important for a virus to make sure that it gets onto a flash drive at any cost. The virus writer does not care whether he kills your flash in a month. He just wants to get his bad instructions onto your flash. This means that he will often just have his program write Over and Over and Over again to your flash drive blinking its light all day long. When you’re doing a hundred reads and writes a minute, soon your millions and billions of operations are exhausted and gone.

If you notice your flash drive acting strange or slow you might only have a few more chances to rescue your data. Though you should always keep backups of your flash somewhere, in this situation make a special backup as soon as possible! You usually have a few more Read operations than Write operations with your drive and that could save your data. In the fourth tip of this series I will go into detail on the programs testdisk and photorec and which can be used to rescue files on a drive that Windows/Linux/Solaris will not read.

There are also major issues with fake drives. Beware! My counterparts here at Mpwapwa have seen several weak flash drives labeled “Sony Vaio” which will report to Windows (or Linux, Solaris) that they are, say, 32gb. When you put files onto them the files appear to transfer. This is fake though, the real size of the drive is 512MB. When you take files that are bigger than 512mb off of the flash again it will say that your file is corrupt. We have also seen that these flash drives fail much quicker than other flash drives.