Sharing CDs With The Entire Network.

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.

Flexibility

flexibility is important in any network sharing solution. This is achieved by supporting a variety of protocols over standard networks including: Microsoft Windows NT and OS/2; SMB (Server Message Block) over TCP/IP or NetBEUI, Novell; NCP (NetWare Core Protocol) over IPX (Internet Packet Exchange), Unix; NFS (Network File System) over TCP/IP via UDP (User Datagram Protocol), Macintosh; AFP (AppleTalk Filing Protocol) over TCP/IP and Web Browser; HTTP (HyperText Transfer Protocol) over TCP/IP.

Remote Loading Of (D Images And Job Scheduling Of The CD Imaging Process

It is important that CD images stored on the CD sharing server can be loaded from a CD-ROM drive of any client computer on the network. This is a necessity for efficient administration and maintenance. Enabling this remote function should also feature job scheduling, thus allowing multiple CD volumes to be imaged to magnetic media after hours without requiring user intervention.

Web Browser-Based Administration

The server should be designed for an Intranet architecture and its administration controlled through a standard Web browser. This allows the network administrator to control the CD sharing from virtually anywhere on the network. Accessing the unit should be as simple as pointing the browser to either its IP or WINS address.

The CD-server should integrate smoothly into Microsoft, Novell, and TCP/IP network environments. Client computers need to be able to access network CD resources as they would any other network resource. In the cleanest implementations, no unique client-side utilities are required.

TCP/IP

The required configuration elements to enable TCP/IP operation include having an IP address assigned, having a properly specified network mask, and having IP addresses assigned for a Domain Name Services (DNS) server and for a default gateway.

If the network already has a DHCP (Dynamic Host Configuration Protocol) server, a BootP (Bootstrap Protocol) server, or a RARP (Reverse Address Resolution Protocol) server available, then configuring the TCP/IP settings is very easy. The CD server should have a unique MAC (Media Access Control) address that will be recognizable when using any of these three automatic configuration devices. DHCP, BootP, and RARP are capable of assigning all the TCP/IP network configuration options.

Accessing CD images may be accomplished in several ways. The use of a Web browser is generally the easiest, particularly if the -CDs contain HTML-encoded data. The CD volumes appear with their CD directory structure, and files are accessed in much the same way as Microsoft Windows File Manager or Explorer by drilling down through the directory structure to the file. Individual files may also be accessed through FTP where each of the CD images will appear as a directory. The NFS approach allows any NFS client to mount the CD images on the CD server as exported file systems.

Novell NetWare

In a Novell Netware network environment, the CD server appears as a standard NetWare fileserver. When users need to access the CD server from NetWare clients, they should be able to use the same access procedures as for any NetWare fileserver. The CD server should follow standard NCP (NetWare Core Protocol) designed by Novell to respond to application requests coming from client workstations and uses IPX (Internetwork Packet exchange) as its network transmit protocol to transmit the requests for service to the fileserver.

To function as a NetWare server, the CD server must have certain configuration details established. Four parameters must be set: a) a server name must be specified, b) the correct Ethernet frame type must be selected, c) a unique internal IPX network number must be assigned, and d) the correct physical IPX network number must be used for that network segment. The CD server, without any intervention, will sense the physical external IPX and Ethernet frame type numbers and will assign default values for the server name and the internal IPX network number.

Microsoft Networking

The protocol that is used predominantly in the Microsoft Windows environment is SMB (Server Message Block). It intercepts network-related DOS function calls and redirects them across the network to a CD server. SMB is to Windows what NCP is to NetWare by performing similar functions for its clients. The CD server appears as disk shares within the specified domain. Users can access the CD images on the CD server by navigating to them under the Network Neighborhood utility in Windows NT, Windows 95, or Windows 98.

The Net Use commands can be used to assign drive letters to the CD server as a whole or to individual CD images. As in NetWare, the CD server saves the administrator the effort of manually defining a set of users by taking advantage of the users and groups that have been defined in the existing NT domain.

CDs provide the best means for distributing large amounts of data without the worry of virus susceptibility. Networking CDs can provide significant improvements in simplified management, easier configurations and installations, cost savings in both hardware and software, more manageable updates, productivity increases, and better security. The CD server provides these effective solutions and, thus, improves business performance with no added demand on existing network servers. At the same time, CD Servers can empower workgroups in the most cost-effective manner.

Perry Solomon is the president and CEO of Smart and Friendly (Chatsworth, CA). Solomon is the chairman of the market development committee for the Optical Storage Technology Association (OSTA).