MO Better Reliability Safe Storage

By Bill Troop

After a decade of writing on archival storage media, I can honestly report that the $349 Fujitsu MO drive reviewed here is the best, safest removable storage money can buy. It's also among the most convenient: the small, rugged, 3.5" cartridges now store a whopping 2.3 GB of data.

Magneto-optical, popularly known as MO, is the most reliable rewritable technology available today. All other media -- magnetic or optical -- has a downside. MO combines the best elements of magnetic and optical technology.

With MO, the media is heated to several hundred degrees by a laser before it is written to. The heated areas are so small, though, that the media never becomes hot. MO is thus immune to stray magnetic fields, unlike traditional magnetic media like floppies, tape, Zips, hard drives, and Jaz/Orb cartridges. This, combined with the fact that there is no way for the head to contact the media, results in the greatest permanence contemporary technology can offer. MO media is by nature immune to dust, shock, fingerprints, food spills, travel, magnetic fields, and other contaminants. Those are the very things that destroy magnetic media, as well as purely optical media like CD and DVD.

It is a commonplace of the storage industry that MO discs are (1) significantly more reliable than CD-R, CD-RW and the warring family of DVD formats and (2) vastly more reliable than magnetic media. Indeed, as hard drive prices plunge, reliability -- which the industry worked so hard to achieve in the 1990s -- is going out the window. Catostrophic hard drive failures are becoming the norm. And that's good news only for the makers of backup software and hardware. All the more reason why it is crucial to back up. Even some expensive SCSI hard drives are no longer being made to the standards of a couple of years ago, and hard drive manufacturers are beginning to whittle their warranties down from three years to one.

MO versus CD and DVD > CD-R is probably the backup strategy most people now use since CD-writers are fast and the media is the cheapest out there. But CD-R disks are easy to mar to the point that significant data loss occurs. And that's assuming you get an error-free burn in the first place. But even that isn't guaranteed, as the low quality of most CD-R disks on the market today becomes increasingly apparent. The problem is price pressure which has forced manufacturers to put out disks that are worse this year than ever before. I have Kodak CD-Rs that cost $40 in 1994 and still read perfectly today; by contrast, the 'Net is full of complaints about top media from reputable manufacturers today, though it only costs pennies. $40 vs. $0.40 -- you figure out what a manufacturer is going to give you for those prices.

Moreover, CD-R is not, like MO, rewritable; but media cost is so low that most people aren't bothered by that. Although CD-R is probably the most stable of the purely optical technologies, there are many ways in which a CD-R disk can fail, including dye instability, exposure to light, environmental damage, physical damage to the delicate disks, or manufacturing defects. Because CD-R is so inherently fragile, even if you take good care of the discs, it is not uncommon today to make a successful burn, and verify its integrity, yet a week (or a month or a year) later, when you try to read the data off the disk, it's trash.

Why does purely optical media degrade? The textbook answers are exposure to heat, sunlight, and atmospheric contaminants. MO is immune to these factors because it uses strong magnetic fields to write and read but, because the magnetic field must be heated by the laser before it becomes active, it successfully resists any of the forms of degradation to which purely optical and purely magnetic data are subject.

Another problem with CDs and DVDs is in the lamination process -- the glue that bonds the different layers together eventually fails. To keep the cost of CD and DVD media down, manufacturers must use cheaper materials. MO manufacturers have resisted this temptation. And DVD manufacturers are virtually admitting that their media is trash: at press time, TDK announced "Armor-Plated DVD Media" which supposedly, according to the press release, has "a remarkable 100 times greater resistance to damage from everyday use such as scratches, dirt, fingerprints and other contaminants." The new media is to be available in 2003; no word yet on price.

Another inconvenience of CD-R is the limited space: 700 MB is not large by today's standards. DVD-R shares all the same negative elements of CD except space, including, most notably, CDs' lack of built-in error correction. MO, by contrast, is structured like a hard drive, and error correction is built in.

As to the writable form of CD, CD-RW, and the rewritable forms of DVD such as DVD-RW, I have never been convinced that these are viable media for long-term storage; they are at best suitable for temporary storage or data exchange. I have seen too many long-term failures with the phase-change technology that underlies CD-RW and all the rewritable DVD formats. That said, DVD-RAM is the only one of the DVD formats with built-in error correction, and it is a good storage medium, though it isn't as reliable as MO. Yet DVD-RAM is steadily losing popularity to other DVD formats which offer inferior data reliability.