As I wrote yesterday, it appears that Amazon's mysterious Glacier service uses optical disks rather than hard drives. Panasonic has been slogging away for years to make the high-capacity optical a practical archive medium. And last month Panasonic and Sony jointly announced Archive Disc (AD), a 300GB optical disk, with plans to take it to a 1TB capacity.
With optical disk adoption by major cloud players, who add petabytes of capacity each day, this is not a fantasy. But make no mistake: this isn't for home users.
AD uses a Blu-ray laser but the similarities stop there. The discs are dual-sided with 3 layers each side. The track pitch is much tighter - 225µm vs 320µm for Blu-ray discs - as is the data bit length - 79.5nm vs 150nm - achieving 300GB on a single disc.
Laser diodes are cheap but precision mechanics aren't, so this won't be a home device any time soon. Figure that they plan to make money on the media selling huge volumes to a few buyers.
Enterprise users don't have to wait for the coming AD to start using optical libraries though. They already exist.
- Legal. As a write-once medium, Blu-ray discs can meet legal requirements for archived data.
- Long media life. Disks and tapes are usually replaced on 5 year intervals, where Blu-ray archive discs claim a 50 year life, eliminating data migrations.
- Blu-ray drives are cheap, enabling equipment upgrades and replacements at much lower cost than tape drives.
The Storage Bits take
These small optical libraries aren't cheap, but they are much faster than Glacier's 3-5 hour response time. Nor is the legal status of Glacier archives clear.
But as optical technology continues to advance - as it appears certain to do with Panasonic's support and major cloud buyers - optical's advantages over tape will grow. In the era of 6TB hard drives we tend to forget that many businesses don't need petabytes of archive capacity.
If 50TB of local archive capacity works for you today, with the promise of much higher capacities coming soon, then optical may be your solution.
Comments welcome, as always. I'd like to hear from people who maintain archives today. What's working for you now and what do you need for the future?