Sharing CDs With The Entire Network - Technology Information

Computer Technology Review, April, 2000 by Perry Solomon

This article begins a semi-regular series written by a member company from the Optical Storage Technology Association.

Organizations are increasingly determined to develop means of economically accessing their data for more responsive customer support, more competitive operations, and more accurate decision-making. Many businesses have discovered that today's network storage solutions allow them to store, index, and retrieve documents, data, and images online. The goal is to provide authorized network users with transparent access to on-line information repositories. In this way, a single search will be able to access information in any of the organization's online repositories.

The CD sharing network server is a solution designed to deliver CD-based resources to any number of users in a networked environment. Properly implemented, it can offer quick, cost-effective, and easy sharing of CD-based data regardless of platform. These servers eliminate the need to pass around popular CD discs and eliminate the difficulty of keeping track of the whereabouts of discs when they are shared among many users. The advantages of the CD network include the ability to provide the required resource to more than one person simultaneously.

One approach to a dedicated CD server is to create a standard file server running an operating system such as Microsoft Windows NT, Novell NetWare, or a Unix variant provided with one or more processors, large amounts of RAM, and multiple CD-ROM drive towers. Through the addition of magnetic storage for the caching of the CD data, these servers will support multiple simultaneous users, but the required technical skills to install and manage these CD networks will be significant.

A simpler, more costeffective approach uses a direct network-attached thin server, which acts as a CD server and is connected as a node in an Ethernet network. Network addresses can be assigned automatically or entered manually through an HTML-based Web browser.

There are a number of advantages related to convenience and decentralization. Users can access the CD server the same way they log on to a server. There is no need to install special software on the server or the clients, which will save time for the administrator and the users. Another advantage is that everyone on the network, whether they are running Windows, NetWare, Macintosh O/S, Unix, OS/2, or a web browser, can share the CDs simultaneously. Since the CD server is file server independent, it can also be used in peer-to-peer (server-less) environments. In addition, these CD-servers do not require reentry of user and group names and can utilize existing NT or NetWare security resources.

A network plug-in, dedicated CD sharing server is suited for any environment that needs to share CD-based data amongst many users simultaneously. It eliminates the need to purchase and manage multiple copies of CDs and does away with the inconvenience of having to wait for a particular CD to be freed up.

Some examples of the benefits gained by using a CD network include: client workstation installation from a network-attached CD server; software distribution; computer-based training to multiple users simultaneously; and the storage of documents where required by law. The CD server can be the primary means of distributing a myriad of CD-based data on your network: catalogs, computer-based training materials, knowledge bases, software applications, and government regulations to name a few.

Performance

The caching of CD data to magnetic media is basic to the CD sharing server. The CDs are completely imaged to magnetic hard disk drive(s), enabling the user to see what appears to be physical CDs mounted and available on the network when they are, in fact, images of the CDs stored on the magnetic media.

When storing CD data, caching to magnetic hard drives attains the greatest performance benefits. Today's magnetic hard drives outperform the best of the industry's CD-ROM drives in three distinct areas:

A. Average access time--the time that it takes the device to get to the data--which averages l00ms in the fastest CD-ROM drives as compared to 8ms-l0ms for magnetic drives.

B. Sustained throughput, which for a typical fast CD-ROM drive, is no better than 4MB/sec, compared to 12MB/sec to 40MB/sec for a fast magnetic drive.

C. Random read throughput, which is the specification that best illustrates the real performance differences between CD-ROM drives and magnetic drives when multiple users are attempting to access data simultaneously.

The real performance advantage of a magnetic drive is in the random throughput arena. This is where the architectural differences between CD-ROM drives and magnetic drives become very apparent. By design, CD-ROM drives and magnetic drives perform best when accessing data sequentially, but the differences in head/positioner assembly design--lower weight and lower inertia in the magnetic drives--and the higher rotational speeds of the magnetic drives, provide them with a substantial performance advantage in accessing random data. These performance differences will typically exceed 20:1 in favor of the magnetic drive.