While the diskettes that go into a floppy drive can be taken in and out, the hard drive generally has no removable parts. Hard drives can range in size from 20 to 1000 MB or more. Hard drives are usually 10 to 20 times faster than floppy drives. Data can also be destroyed by users who inadvertently or maliciously instruct the computer to delete files. Disks can be damaged by extreme heat or magnetic fields.
Computers are also subject to fire, theft, water damage, and other disasters.
For these reasons, most companies create backup copies of their data. These can be stored in a safe or at another location. Some insurance companies require businesses to do this with important data. Backups can be set up to occur automatically every day, week, etc. For a moderately- sized system, a backup of 10 to 50 megabytes can take 20 to 40 minutes.