MO Storage Hangs Tough

By Lowell Rapaport

Lower prices and higher capacities have boosted sales of 5.25-inch magneto-optical jukeboxes. Despite new alternatives like DVD and RAID/tape combos, MO is still the king of speed, capacity and acceptance.

Last yearıs introduction of 5.2 gigabyte (GB) 5.25-inch drives gave magneto-optical owners and prospective buyers new reason to have faith. With little or no increase in the price of discs or drives, every major MO jukebox manufacturer was able to double the capacity of its storage solutions.

By next year the market will surely see 9+ GB MO platters, but magneto-optical faces competitive threats on two fronts: namely, DVD-RAM at the low end and combinations of RAID and tape at the high end. The question is, can magneto-optical technology continue to be the most efficient way to serve the needs of document professionals?

In the last year, sales of magneto-optical jukeboxes have been growing, partly due to declining prices. For example, market leader Hewlett-Packard (Rockville, MD 301-258-2000) reduced prices on its jukebox line between 14% and 20% shortly after 5.2 GB MO drives debuted.

ıMO Jukeboxes have come down in price, making them more affordable to more customers,ı says Richard Game, vice president of sales and marketing at jukebox management software vendor KOM (Kanta, Ontario 613-599-7205) ıLarge jukeboxes in particular are selling better since they started out with better price/performance ratios.ı

Cheaper CD jukeboxes may sell in far higher numbers than MO, but they have never really been a competitive threat in the high-end market. CD canıt match magneto-opticalıs interactivity. Even though software advances have simplified recording on CDs inside a jukebox, the recording process still requires more planning on the part of system administrators and end users.

CD also suffers from low capacity (650 MB per disk versus 5.2 GB for MO) and low speed (200 msec access time for CD versus 20 msec for MO). Clear evidence of this drawback is provided by the number of software and hardware devices that now let users cache CDs -- sometimes dozens at a time -- on hard drive storage.

DVD technology at least partially solves these problems. DVD is looked on by many people as the logical successor to CD technology, primarily because of the similarity between the two technologyıs form factors. However, DVD-RAM can also be a replacement for magneto-optical. Like MO, DVD-RAM disks are encased in rigid plastic cartridges. While the DVD-RAM jukeboxes offered to date have been based on (single-side reading) CD jukeboxes, you could, theoretically, use the disk-flipping capabilities of MO jukebox robotics to take advantage of dual-sided DVD discs. Current dual-sided DVD-RAM discs have the same 5.2 GB capacity as the latest 5.25-inch MO platters.

However, there are several factors preventing DVD from challenging MO in many applications. First, while DVD media is less expensive than MO media ($40 for dual-sided DVD-RAM versus about $100 for MO), DVD is also considerably slower. Access time for DVD is ten times that of MO (200 msec versus 20 msec), and the transfer rate is one quarter as fast (1 Mbyte/sec versus 4 Mbyte/sec).

And there is still confusion and doubt about the future of DVD recordable formats. DVD technology is divided among DVD-ROM, DVD-R, DVD-RAM, DVD+RW and DVD/RW. Not all these formats are compatible. While DVD-RAM and DVD-R have a clear head start, there is still concern over which format will eventually prevail. If you need storage now, magneto-optical is an established industry standard, and you can count on a useful product like extending at least ten years.

MO Versus RAID/Tape

The RAID/tape combo is newly competitive due to falling hard disk prices and larger and faster tape technologies, like AIT and DLT. The trend is continuing. Hard drives have reached 36 GB capacity, and new tape drives like AIT-2, SuperDLT and Linear Tape Open (LTO) will arrive this year with capacities greater than 100 GB per tape.

The RAID/tape combo has a lot of appeal to some. Many jukebox management systems already cache data to hard disk anyway to speed access. If files you need are cached, there is no operational difference between a magneto-optical jukebox and a tape library. Tape is also unequaled for storage capacity. The largest magneto-optical jukeboxes store about 5 terabytes (TB). A tape library can have double that capacity. Furthermore, tape media is much less expensive than MO or DVD media. $100 will buy a single 5.2 GB MO disk, two 5.2 GB (10.4 GB total) DVD-RAM disks, a single 35 GB DLT tape cartridge or three Travan NS10 tapes at 10 GBs each. And compression can as much as double tape capacity.

Tape, of course, has limitations. Time to data is measured in seconds -- three orders of magnitude slower than for MO. For document imaging users who need to track down individual files, tapeıs slow access speed usually relegates it to backup duty.

Tape libraries canıt handle large numbers of users very well either. Tapes can take many seconds or even minutes to mount. If you have a lot of users seeking files from different tapes, it can lead to tape thrashing and wasted time. Add to this the fact that tape drives require more maintenance than MO drives and that tape wears out, especially when used regularly. Most tape users replace the media every 18 to 24 months. For a large document warehouse, this could add up to a big long-term expense.

RAID has limitations too. As much as hard drive prices have come down in the last year, the incremental cost of adding RAID storage is higher than MO. Add an extra MO disk to your jukebox and the cost is about $100. 5.2 GBs of hard drive storage is about two to three times that cost. As tape libraries get larger, RAID systems would have to get larger to keep pace.

The RAID/tape combo might be suitable if your image or document access needs follow the 80/20 rule -- with the 20% of files that are most frequently accessed on RAID and the remaining 80% on tape. However, if your documents are accessed with more uniform frequency, the data stored on relatively slow tape drives could easily turn into an albatross.

Who Should Use Magneto-Optical?

According to Gordon Thayer, reasearch and development program manager at Hewlett-Packard, most MO jukebox users donıt keep media off-line. ıWhen users accumulate more media than can be handled by a jukebox, they will usually acquire an additional jukebox,ı he explains. If users are willing to install additional jukeboxes, then there is a clear need for near-line access. ıBesides,ı Thayer points out, ıThe cost of a jukebox is lower than the cost of paying a system administrator to swap disks in and out of a single jukebox.ı

In the end, combined RAID/tape solutions will work only for those users who would otherwise keep large amounts of data off-line. Magneto-optical is also the best solution if you have large numbers of users. The more users you have, the more likely it is that media will have to be swapped. No removable storage medium offers faster access to data than magneto-optical. So until a faster alternative comes out, MO is it.

Hewlett-Packard
Palo Alto, CA 905-206-4383

Plasmon
Eden Prairie, MN 612-946-4100

Maxoptix
Fremont, CA 510-353-9700

Disc
Milpitas, CA 408-934-7000

Pinnacle
Irvine,CA 408-934-7000