So far as I know, the best way to store modern computer data for long-term purposes ("archival storage") is via "Magneto-Optical" or "MO" technology. It is based on a Natural phenomenon used by geophysicists, to read Earthly magnetic-field data that is hundreds of millions years old. That qualifies as superb "data retention" by any ordinary standard!

Basically MO technology starts with a "magnetically hard" substance that could be used to make a nice strong permanent magnet. This particular substance needs to be somewhat special, because it also needs optical properties that depend on the orientation of its magnetic field (I've linked an article below).

Anyway, all magnetic substances will lose their magnetism if the temperature rises enough (different for each substance, the particular temperature is called the "Curie Point"). In MO technolgy, a laser is used to heat a tiny spot on the data-disk, and a magnetic field can be applied to affect the orientation of that spot as it cools down and becomes magnetically hard again. (The Earth's magnetic field affects magnetic grains in cooling lava, and so geophysicists know the planet's magnetic field has flipped quite a few times during many millions of years.)

The optical properties of the cooled substance reflect a laser in different ways, depending on the way that spot has been magnetized (Kerr Effect).

For a number of years various manufacturers offered Magneto-Optical products. They are now being discontinued for several reasons. A few of those reasons are:
1. slow writing time compared to other products
2. competing products (like rewritable DVDs) arrived that hold more data
3. competing products arrived that have no mechanical parts (FLASH)

However, no other available technology appears to be matching the Long Term Data Retention possible with MO data storage. I'm linking a case in point, below.

Former MO manufacturers should seriously think about getting back into the business, specifically focusing on archival-storage products. Improvements such as blue lasers and perpendicular recording can be incorporated to increase data storage.

There is also a way to incorporate MO into a "normal" computer system such that the users seldom need to worry about slow write times. It might be possible to deliberately make a slower reader/writer, just to allow even more accurate and smaller and numerous data spots!

I'd also like to suggest a variant on "standard" MO disks that may be more quickly write-able. I'd still use a protective shell, to prevent scratches, but the disk itself would have a metal core (aluminum) and the MO substance would coat both sides. Inside the drive we would heat the whole disk (perhaps by magnetic induction)to a temperature a little below the Curie Point for the MO substance. Now the laser, instead of having to heat the spot on the disk from room temperature to the Curie Point, only needs to heat it a few degrees, taking a lot less time to write a spot of data. A drawback could be that the spot needs to COOL fairly quickly to freeze the data in place, which normally happens because a normal disk is mostly at room temperature. So, we can't heat the whole disk TOO close to the Curie Point, it needs to be far enough below that Point to allow fairly rapid cooling.

If that notion doesn't work out so well as I hope, then the don't-worry-how-slow-it-writes technique can still be done; it involves some help from the hardware and the Operating System, so I recommend getting the fast-responding Linux community involved in drivers and "default working pathways" and such.

Here is a description of some basic features of the Archiving Computer:
1. The regular hard disk drive should hold the OS and applications.
2. All data should be saved on the MO disk, but INDIRECTLY.
3. The system should be protected by an Uninterruptable Power Supply.
4. The system should incorporate a RAM disk the same capacity as the MO disk (say 8GB if the MO is 8GB).
5. The system UPS makes RAM disk cheaper than even the one I'm linking below (no backup power needed on-board, just I/O).
6. The RAM disk is be set up as an image of the MO disk.
7. Applications interact with the RAM disk faster than even a hard disk.
8. A background task can take its time copying new data to the MO disk. If smart enough, it might normally be able to avoid re-recording already-existing data, and could even automatically ensure files are defragmented, for faster reading later.
9. The MO disk reliably retains data for 40+years, possibly for thousands or millions of years if kept away from fire (no one knows for sure).
10. If the MO drive breaks, just replace it. The data is safe on individual disks. (This is another reason for manufacturers to get back into the business, maintaining stored-archive-retrieval technology.)
-- Vernon, Nov 06 2008

A RAM-disk card that plugs into the motherboard. http://www.gigabyte...aspx?ProductID=2180
As mentioned in the main text [Vernon, Nov 06 2008]

MO information http://en.wikipedia...gneto-optical_drive
As mentioned in the main text [Vernon, Nov 06 2008]

CDRs can't be trusted http://hardware.sla...11/06/1549256.shtml
As mentioned in the main text [Vernon, Nov 06 2008]

Perpendicular Recording http://en.wikipedia...endicular_recording
more information [Vernon, Nov 06 2008]

Curie Point http://en.wikipedia.org/wiki/Curie_point
more information [Vernon, Nov 06 2008]

Kerr Effect http://en.wikipedia...o-optic_Kerr_effect
more information [Vernon, Nov 06 2008]

Some NASA data that wasn't archived very well http://www.abc.net....8/11/10/2415393.htm
Even without DRM (digital rights management), data can become inaccessible if the hardware becomes obsolete. This stresses the need for SOME sort of standardized archiving hardware that is simply not allowed to become obsolete. One thing about MO technology, as it improved over the years, it was always backward compatible. The most recent 3.5"/90mm drive can work with disks that can hold 2.3GB of data, but the drive can also read original disks that only held about 128MB of data. It is to be hoped that if the tech improves still more, they would still retain backward compatibility. [Vernon, Nov 10 2008]

RAID has its own limitations http://blogs.zdnet.com/storage/?p=162
I'm going to assume that other versions of RAID have a similar potential problem, involving different disk-drive capacities. [Vernon, Nov 10 2008]

I am right now browsing the net from a computer that has a 250 G hard disk. The breakup? about 75% videos I have watched or intend to watch or want to look up something like "wasn't that scene in there" or something like that.

Music takes up a sizable portion of the remainder. Ebooks in pdf format are there, just in case somebody needs them. Then there is archived text because internet access is slow and expensive.

Archiving, to whatever medium, will require the user (system administrator, BOFH) to make an intelligent decision as to the necessity of storing only that which is irreplaceable.

In my case, that portion consists of my work, photographs, etc., and constitutes only a tiny portion of the hard disk.

So, if you think there is a great business in reviving the MO technology, go ahead and do it. I will buy one to archive my data if it is cheaper or more convenient than setting up a RAID and swapping out bad disks.

But saying manufacturers "should" make MO disks smacks of advocacy, no firm intent on making their investors stay solvent is going to manufacture stone age archival tools just on the say so of an idea on a website.

Good Luck.
-- neelandan, Nov 08 2008


I used to use MO disks for the backup of payroll information of over 100,000 local employees. I can't remember the name off hand, however they were CD sized but in cartridges, kind of like some of the earlier CD drives that required a cartridge to be able to read the disc.

I never had an issue with them, and did daily, weekly, monthly, and yearly backups, including of course, redundant copies to be sent to our head office every week.

I really enjoyed opening the little slide door on the media and looking at the disc. The colors on it dispersed similar to a CD, however it was more of a red/blue/magenta higher contrast look.

This was an OS/2 SCSI setup as well.
-- Giblet, Nov 08 2008


Compelling and informative,ut it does smack of advocacy, but it also hints at a path for advertising for all those Mom's with digital pictures. In any case bun (+) for encouraging me to search eBay for a drive and media. People ask me all the time about archival media and my previous answer was USB hard drives stored in a safety deposit box. I wonder how long they last?
-- MisterQED, Nov 08 2008


[miasere], I recently saw an article that might answer your question (see link).
-- Vernon, Nov 10 2008


Its easier to make an extended version of RAID than to resurrect the MO disk.
-- Spacecoyote, Nov 11 2008



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