Data Retention for legal reasons
Joe K, The reason why companies invest in say optical storage is for legal reasons.
Backing up stuff onto hard drive is ok for short term storage but long term storage is needed on something that does not require power.
Ever seen anyone guarantee a hard drive for 20 years ?
Take for example a car insurance company, They have to keep backed up data going back 6 years.
If old customers data is stored on optical media then there is no power requirements in keeping data. Power is only required to read back or write to.
Also this data is guaranteed for 50 years on UDO media.
Or another example is the film industry when shipping mastered films to different countries (say for a world wide release of a film at the same time).
Shipping mastered films on either hard drive or LT backup take is unreliable due to vibration, temperature.
Yes the film industry could use blue-ray DVD but then if it got pinched then anyone could view it.
Also mastered films tend to be larger (data wise) than the finished product.
So when it comes to security, you'd ideally want a medium format that not many other people use, less chance of a security breach then.