long-term storage and backup

securing internal hard drive data

syncing data between network devices

logs of network activity

Blu-ray disc

USB drive

DVD

CD

A head actuator on the hard disk attaches to arms that move it.

The mechanism presses down hard on the disk's recording surface.

The platter spins to create a cushion of air between it and the read/write head.

Each platter has two read/write heads, one for each side.

provide secure backups

offer data duplication

outperform mirroring

require encryption

data to move freely between storage and memory

contaminated items to be cleaned

items to be recorded magnetically on its surface

audio to be translated from analog to digital

optical technology

ceramic platters

reliance on ROM

lack of moving parts