It's bought and bartered every day. It differentiates successful companies from marginal ones. It forms the foundation of every successful enterprise. And, when it's transformed from its raw state into intellectual property, its value soars beyond calculation.
Like any other strategic asset, information must be protected from loss, corruption and theft. But how?
This primer is an important first step in evaluating and understanding your options in storage, especially optical storage. It explores the challenges of data proliferation, compares various approaches to data protection, and outlines specific optical technologies that help address the challenges of data storage in the information age.
No single document has all the answers. But, with this primer, you can begin to evaluate your options in optical storage, and understand how today's technology can protect your company's most valuable asset into the future.
Dealing with Data in the Information Age
Remember the one-gigabyte hard disk? A true breakthrough in its day, it's now virtually obsolete. These days, PCs need that much space just for e-mail and attachments.
The fact is, storage requirements among network clients are exploding, and the pace of data accumulation is not slowing. Increased Internet use, data mining, database access, e-mail traffic, and other common applications are contributing to information overload on networks worldwide. The problem is especially acute in the service sector, imaging environments, customer service departments and other environments that maintain account information online. And, while the demand for storage space is increasing, so too is the need for instant access to that data. In other words, it's not enough to find a place to put it; you have to put it where you can get it back fast.
Where to Put It
There are four broad categories of data storage. Depending on the sensitivity of data, number of data users, frequency of access and your storage budget, you might use one or all of these strategies in your company.
Three Basics of Storage
No matter what combination of storage strategies you choose, three basics must be met.
The data you store today must be readable in the future, and that's what industry standards are all about. If you store data on optical disks or magnetic tape, make sure you use formats that are supported by ECMA, ISO, IEC and OSTA. These industry consortiums define standards for hardware, data interchange, media and write procedures. They help protect your data by making sure that the data you store today is readable in the future. They also help protect your budgets by allowing you to choose systems and media from a variety of vendors instead of being locked into one vendor with proprietary technology.
Few people calculate the cost of downtime, but minutes or hours of downtime add up to tens or hundreds of thousands of dollars per year in lost productivity, lost revenue and increased expenses. Plus, access is a reasonable expectation among data users: they expect to be able to store and retrieve data quickly, and share and distribute it freely. Any storage solution — especially a storage solution for an increasingly digital, increasingly interconnected world — must store data within easy reach, and keep it online virtually around the clock.
If information is important enough to be backed up, then it's important enough to be backed up accurately. Data users expect complete accuracy, protection from loss, and when the inevitable disaster happens — facility damage, virus infection, system crash or operator error — they expect data to be restored quickly. In fact, restoring data accurately is the only reason for backing it up in the first place. That means any storage solution you choose should include built-in utilities for data protection, overwrite protection, error-checking and disaster recovery.
Your Options in Optical Storage
How It Works
Optical drives read data by bouncing a laser beam off the recording layer of an optical disk, and registering differences in how the light is reflected.
The read-write head contains a laser, mirrors and lenses to send and receive the reflected light. As the head moves over the disk, it focuses its laser on the disk's data layer, and translates the reflections into the 1s and 0s of digital data. While all optical drives read data in a similar way, different technologies use different methods to record data.
CD-ROM, CD-R (compact disc-recordable) and CD-RW (compact disc-rewritable) drives record data by putting marks on a disk's recording layer. A finished disk contains marks and spaces (i.e., non-marked areas). Each mark or space represents one bit of data. Marks are non-reflective, spaces are reflective. Since they reflect light differently, the laser is able to read the recording surface and translate recorded data into 1s and 0s.
Magneto-optical (MO) technology takes a different approach. Instead of reading the intensity of reflected light, an MO drive reads the direction of reflected light. The recording surface of an MO disk is magnetic, much like a common hard disk. To record data, a laser heats a tiny spot on the disk directly above the recording layer. Once it reaches a certain temperature, the spot on the disk's recording layer can be manipulated by a magnet, which moves the recording material in one of two directions. Each direction reflects light differently, allowing a low-power laser to read the reflections and translate what it sees into 1s and 0s. Unlike other technologies, the MO recording method and MO media support a virtually unlimited number of rewrites, with a media shelf life of at least 100 years.
There are currently over 800,000 5.25-inch optical storage drives in operation worldwide. Though not as ubiquitous as hard disks, microfilm readers or file cabinets, optical drives and jukeboxes are quickly being implemented in computing environments around the world, especially as the importance and quantity of corporate information grows. Optical storage is uniquely designed for an increasingly digital world, where information must be stored safely, shared globally, and accessed instantly, sometimes over vastly distributed networks.
There are three basic categories of optical storage: CD-ROM, rewritable and WORM (write once, read many). All are viable, all have strengths and weaknesses. Here's a quick look at the technologies and most common recording formats in use today.
There are many flavors of optical storage. Here's a quick comparison of the most common recording formats in use today.
MO drives use a laser and magnet to record data on optical disks. The write procedure causes no measurable wear on the media, so write cycles are virtually unlimited. Read/write speeds are extremely fast — just slightly slower than hard disk speeds — and data reliability is extremely high, with a hard error rate that is 10 times better than half-inch tape.
MO disks and drives are governed by industry standards set by ANSI, ISO and ECMA, which define physical form factors, logical sector formatting, registration of bad sectors and more. Industry standards assure backward compatibility among multiple generations of MO disks. Realize, however, that media interchange relies on compatible file systems; MO disks stored under Windows 95® are accessible only on another Windows 95 or compatible file system.
Most CD-RW drives employ the phase-change recording format, which uses a plastic disk with a metal recording layer to store data. Heat generated by the drive's laser focuses on the disk's recording layer, and changes spots on the disk from an amorphous to crystalline state. Whenever a spot is reheated, it changes back to an amorphous state. Writing data consists of heating the desired spots to change their state. When reading, the laser detects differences between the amorphous and highly reflective crystalline spots. Because a high-intensity laser is required to heat the recording layer, the disks are very stable and their data will remain unchanged for up to 100 years. Phase-change recording has one primary limitation: the high-intensity laser is expensive compared to most other optical read/write heads.
Bubble-forming devices use a laser to vaporize a disk's dielectric recording surface, causing small bubbles to form. The bubbles change the reflectivity of the disk's recording surface, a difference that is detected during reads.
Most rewritable MO devices use a two-pass write procedure: the first pass erases the disk's surface area, the second pass records information. An emerging technology known as LIMDOW (light intensity modulation/direct overwrite) recording allows one-pass writing on special MO disks. LIMDOW devices will offer higher write performance than today's MO technology since the device writes directly to the media substrate with one head pass. However, the media and hardware are more complex and more expensive. For that reason, LIMDOW is not currently a widely accepted format.
Digital Video Disk (DVD) closely resembles a standard CD in size, color and physical format, but holds approximately seven times more data. A typical CD holds about 650 MB of data, whereas today's DVD-ROM disks hold 4.7 GB, with a target capacity of about 17 GB in the future. Recordable and rewritable versions of DVD exist today as well. A two-hour feature-length movie can fit on a DVD, making it an attractive medium for the entertainment industry as well as for PC makers. In addition to DVD-ROM, DVD-recordable technologies are also becoming available, with multiple technologies now competing for dominance in the market.
How to Choose
By Data Requirement
The key to building a long-term storage strategy rests in knowing the role of data within your company, and understanding the expectations of those who use it. Here are few checkpoints to consider.
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© Hewlett-Packard Company 1999Francis Bacon