work environment. One solution is networked CD-ROM servers, which are the focus of this month's Lab Report.
Defining the Field
We asked manufacturers to provide a stand-alone server providing support for Windows NT and NetWare and containing from seven to 14 internal 8X-to-12X CD-ROM drives. The systems had to be configured for a 10Base-T Ethernet network. We set an arbitrary maximum cost of $20,000. We excluded non-independent server solutions and jukebox systems that don't keep data constantly available on-line.
The six systems that we tested come from manufacturers who specialize in
CD-ROM server
solutions: Boffin, Excel Computer, Micro Design International (MDI), Microtest, Microtest Enterprise Group, and TAC Systems. During our evaluation, the measured performance of these systems ranged from superb to unacceptable. We exercised them when serving single clients as well as multiple clients in a heavy-traffi
c environment.
Four of the systems, the Boffin 7 Bay Tower, MDI CD-Express Connect, Microtest DiscPort Tower-7, and TAC Systems HotSwap LanRedi TowerDrive, are non-PC servers. Each is built around a smart SCSI-to-Ethernet interface that contains all the hardware, software, and processor power required to perform as an independent file server with few or no external components. The units from Boffin and TAC Systems use implementations of the Axis StorPoint CD-ROM server controller. The two devices from MDI and Microtest use proprietary designs.
The other two systems are built around more conventional Intel Pentium systems and come complete with system board, memory, hard disk, network interface cards (NICs), and video subsystems. To this the manufacturers add all the software and hardware needed to create a system that can serve CD-ROMs.
We were unable to get two additional systems that we received to run. One, a Cutting Edge CDPowerServ, was configured for NetWare, but not Windows NT; the N
etWare software was inoperable. Our attempt to install and configure NT -- despite consultation with Cutting Edge and its network software supplier, Ornetix -- was unsuccessful.
We also passed on a Plextor PlexServer NT system. The device arrived with 16 MB of RAM, which Plextor said was the standard configuration for the unit. The software that Plextor provided, however, clearly states that it requires a minimum of 32 MB to run. As received, the system would boot but was unable to run any benchmarks.
Setup of the MicroTest DiscPort Tower-7 was problematic. The provided software did not work, but we were able to set it up using a separate PC as a server. And the TAC Systems HotSwap LanRedi TowerDrive ran two of our three performance tests but could not complete the full set. TAC tentatively attributed the cause to a problem in the firmware on the Toshiba CD-ROM drives.
(Dis)Economies of Scale
The need for shared access to CDs generally occurs first at the department or wor
kgroup level. Most existing networked PCs don't have CD-ROM drives. And while the price for an individual CD-ROM drive is relatively low, equipping each workstation in a department or workgroup with its own drive is not cost-effective. A multiplicity of drives implies too many copies of applications, data disks, and license agreements.
As deployment naturally evolves to the enterprise level, other problems crop up. Logistics aside, the massive distribution of CDs is proscribed in situations where data is updated frequently or security is a concern. Networked CD-ROM drives, by comparison, incur lower hardware and software costs and eliminate the need to retrofit each PC in a workgroup.
One Goal, Many Paths
Network administrators everywhere must solve several concurrent problems. They must give access to data to many users over a network. They must serve an increasing number of discs. And, on the practical side, they must keep administration and configuration chores to a minimum.
Several different solutions are currently used.
One common method of networking CD-ROM drives is simply to attach them directly to an existing file server. This solution requires a file server that has sufficient processor and memory resources available. This works well for single-protocol workgroups where administration is located close to the server hardware.
Another solution, the peer-to-peer approach, is common in the Unix world. Software loaded on each workstation communicates directly with networking software loaded on a dedicated CD-ROM server. Using existing workstations in this way makes for a cost-effective solution. But the client software consumes resources on every workstation and creates additional administrative chores.
A third solution, using a dependent CD-ROM server, lets you connect a series of CD-ROM drives or a tower unit anywhere on the network. Although the dependent server has no direct connection to its supervising PC, it still requires a software module on the serve
r to control it. The main disadvantage of this approach is that CD-ROM requests must travel twice on the network -- once from the client to the server, and again from the server to the CD-ROM tower.
A high-performance, low-impact solution can be obtained using an independent CD-ROM server that connects directly to the network and operates without the aid of any file server. The CD-ROM server contains its own software and hardware, does not tax other file-server resources, and communicates directly with clients.
Because an independent CD-ROM server appears as a true file server to the network, it doesn't require you to load special software onto clients, thus eliminating the need to distribute, configure, and update the clients. Adding an independent CD-ROM server to the network is quick and easy, requiring only standard network OS management utilities. Some independent CD-ROM servers offer support for multiple protocols. A single server, for example, can operate simultaneously in NetWare, Windows,
OS/2, Unix, and Web environments.
Contributors
Andrew Froning
, managing editor/NSTL
Dorothy Hudson
, project manager/NSTL
Steve Platt
, director of electronic publications/NSTL
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Centralize Your CD-ROMs
