If our hard drives are reaching storage capacities of over 100 GB, then why can’t we use the platters inside as the new CD/DVD storage discs? I understand that usually 2 or 3 platters are used per hard drive, but it still seems like these should have a better chance of being used in the future than regular plastics. And we can read/write to them faster.
Sorry about the ambiguous title, I’ll do better next time.
As magnetic media, the platters are inherently less durable than a CD or DVD. But you could use 'em like floppies.
Thinking about it a little more, I think there’s limited demand, and that would really kill it. How many people need a storage medium larger than a DVD (8 GB, IIRC).
As I recall, the old Syquest and Iomega removable drives were exactly that - hard drive platters which could be removed from the drives. The Iomega Jaz drive had 1GB capacity with that technology.
I don’t think we’ll see 100GB removable magnetic drives. The platter is a very expensive component, so a 100GB cartridge would not be much cheaper than a complete 100GB hard drive. And if you separate the platter from the read/write head and actuators, it will be very difficult to align them correctly each time you insert the cartridge. Also, a removable drive will be open to the air. Even with an enclosed cartridge, some airborne dust will stick to the surface and destroy data. Hard drives are assembled and sealed in cleanrooms so they don’t have this problem.
There is demand for >8GB storage, but the most cost-effective solution is to use entire hard drives as removable cartridges. There are external USB and FireWire hard drives specially designed as portable data storage (compact, lightweight, and run on power supplied through the USB or FireWire cable). The IBM MicroDrive (recently bought by Hitachi) is even more impressive - it works just like any Compact Flash memory card but there’s a tiny 1GB hard drive inside the cartridge.
The platters are fragile. FRAGILE. and muich more expensive than plastic CDs.
As said before, FireWire hard drives are the current portable high-capacity storage.
LaCie has introduced for $1000 a 500 GB portable FireWire 2 hard drive. Coolness abounds. For smaller drives, prices get more reasonable - I think the 200 GB can be gotten for about $400 I think. http://www.lacie.com/
100 gigabyte hard drive… $150.
100 gigabytes worth of CD-RW’s… $30.
I think that clinches it.
Last time I looked a standard deal on CDRW disks was about a buck or so apiece which gives about 19.2 gigs for 30.00. Did you mean CDR disks?
200 GB hard drive (Microcenter, after rebate) - $200
80 GB of CD-RW’s - free after rebate.
Still works in your favour… 
i have read in “MIT’s Technology Review” mag, that kodak is developing a “holographic” that is some twist on optical disk that is CD-sized and holds 200 gigs.
the reason that hard disk is faster is that the reading head is much lighter than a Laser/Lens.
on the other hand its a precision assembly that would be hard methinks to implement in a removable drive. you know a hard drive is mostly airtight with just a small filter to let expanding hot air out and back in. even small dust particles would fuck it up.
the beauty of optical drive is that the surface may be slightly scratched and it still works, because the actual data surface is way below the plastic. this would not work with a magnetic disk 
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10x 700MB 80min CD-RW Media 50 Piece Cakebox
Price: $ 34.50
Both, actually, but I mucked 'em up… 200 gigs of CD-R’s is $30, 200 gigs of CD-RW’s would be $60. Still comes up greatly in favor of CD’s.
True, but not to the degree that there’s demand for CDs or DVDs to store things. The average person doesn’t need more than a DVD.
Of course, that’s going to be false someday soon.
On the demand for large storage:
There really is a crisis in backup storage nowadays. There has always been a “Memory Hierarchy”:
- Registers.
- Cache (or caches)
- Main memory. (Used to be a solid state “secondary memory” next.)
- Disk drives.
- Tapes.
As you go down the list you have: greater capacity, slower speed, lower cost per byte.
But the advances in disk drives has overrun tapes. The cheapest way to back up a 100G drive now is another 100G drive. You don’t have the option of “well for a tenth of that, can I get something slower but the same capacity and removable?”
A DVD just doesn’t hold enough to make backing up a 100G drive as simple as it should. It’s like backing up 40M drives on floppies. Thanks to blue light and layers, DVDs will get better, but disk drives will outpace that easily.
What are you going to store those 500 hours of video of your kid’s first year on?