Schultze, what was the reason given for not using a flash drive? Purely for backups, I don't see any reason they shouldn't be used other than cost/capacity, where hard disks are far better.
Personally I backup to hard disks purely for capacity. There is no other medium that offers the cost/capacity performance combined with a big enough size. I use software to synchronise my main desktop copy to the backup drive.
The reason given not to use flas drives where the high failure rate over prelonged periods (even the big brands, and is was a recent test).
And they are not able to contain information over a longer period due to the design of flash drives.
Flash drives use a charge to retain information, the moment this charge runs out the data is lost. Hard drives use magnetical energie to store information, this also deteriates over a given period, but this takes longer than a flash drive to lose all charge.
it was quite a while ago when I came by this subject in school, but basicly it workes like this:
There are to types of flash/ssd memory. One uses permanent power and one is none-powered. The powerd one is like the ram in your computer, it need continious power to retain its information. This can be done by a battery. They other one is a "none-powerd" type, thuis one uses capacitors to store information. A charged capacitor represents a 1, and a un-charged one a 0. But capacitors that are charged lose there charge over a period of time. Although slow, the flash drive will lose all it's information faster than a hard drive does.