The main drawback of USB flash drives is their limited write and erase cycles. One can only be written and erased about 100,000 times. While this may not greatly affect the average user, it should be a major consideration for users who intend to use the thumb drive to run an operating system or application software.
Thumb drives are designed to be compact and portable, but their small size makes them easier to misplace and lose. To remedy the situation, some manufacturers design flash drives in a way so they can be attached to lanyards, necklaces and key chains. Flash drives are notorious for spreading computer viruses. If the USB drive lacks a write protection mechanism, it instantly becomes infected when a virus-contaminated computer is used to access its contents.
The price per unit of storage of USB flash drives is higher compared to that of external hard drives. They are also smaller in capacity. Flash drives can have up to 128 GB of storage while external hard disks can have up to 2 TB of storage. Flash memory is easily susceptible to static electricity and even the smallest electric charge can lead to data loss and irreversible damage. The main redeeming quality of flash drives is that they are portable and convenient.