NCR's WorldMark 4300 Terminal Server lets IS departments provide continuous computing through thin-client terminals that access a fault-tolerant central storage system. The combination of the WorldMark 4300's hardware; Windows NT Server 4.0, Terminal Server Edition; and NCR's LifeKeeper 2.0 clustering component brings high availability and thin-client computing to the enterprise forefront. I tested a WorldMark 4300 in the Windows NT Magazine Lab to see if NCR's solution successfully implements thin-client technology.
And in This Cabinet
The WorldMark 4300's 77" cabinet houses two 4-way servers and an NCR 6257 disk array subsystem. The two servers are identical in both size and shape. Each server contains four 200MHz Pentium Pro processors, 1GB of memory, a 4.3GB hard disk, and one SMC 10/100 Ethernet adapter. Each server has SCSI connections to the disk array made up of ten 4GB hard disks. Terminal Server and LifeKeeper are installed on both systems, but you must configure them.
The two servers connect to an Apex keyboard/video/mouse switch (KVM switch) that is rack-mounted inside the WorldMark 4300's cabinet. You connect a monitor, keyboard, and mouse to the KVM switch. This configuration lets you toggle between each server's display using the Print Scrn key and lets you use the arrow keys to select each server from a pop-up menu.
New Life with LifeKeeper 2.0
One benefit of the NCR Terminal Server solution is that it brings LifeKeeper to the Terminal Server community. You can use LifeKeeper to achieve the best application availability possible. LifeKeeper lets you depend on maximum application availability during scheduled or unscheduled downtime.
An enhancement to LifeKeeper, known as Cascading Recovery, lets an application endure against multiple failures within a cluster. Thus, an application simply cascades over to another system if one system fails. For a review of LifeKeeper, see "Clustering Software for Your Network," July 1998. For more information about clustering solutions and LifeKeeper, see Mark Smith, "NT Clustering Solutions Are Here," June 1998.
LifeKeeper provides failover capabilities for as many as 16 servers per cluster. This functionality results in higher availability than most NT solutions. LifeKeeper's robust fault-tolerance features provide failover support for the entire server rather than support for only front-end or back-end applications.
LifeKeeper lets users define three components: protected alias host names via its LAN Manager recovery kit, protected IP addresses for continuous access via NCR's TCP/IP recovery kit, and continuous access to volumes for fault-tolerant storage. You can configure these components into a protected resource hierarchy for each logical user group and achieve logical load balancing, to match users to specific Terminal Server hosts. Logical load balancing is different from capacity load balancing, in which users log on and load balancing software provides access via the least busy server.
When a server configured with LifeKeeper goes down, resources move to a different server in the cluster. This migration lets each Terminal Server system provide primary access and fault tolerance in the event of a malfunction. For example, you might have two Terminal Server systems providing thin-client access to two departments. The first department has light users running smaller, code-efficient programs and applications that don't require much memory. The second department has power users running CPU-intensive applications that require more memory and have several applications running at the same time. Users from each department are on separate servers. LifeKeeper exists on both Terminal Server systems, and each user group has a tailored resource hierarchy. If one of the Terminal Server systems encounters a failure, LifeKeeper detects the failure and transfers the hierarchy from the failed server to the running server. When users of the failed server reconnect via normal procedure, they access the failed server's resources; however, the running server automatically services its original users in addition to the failed server's users.
Choose Your Terminal Server Solution
The WorldMark 4300 can be configured with an impressive amount of additional memory, hard disks, and disk arrays for terabyte (TB) storage. The system configuration NCR sent the Lab included two 4-way servers, but you need only add the symmetric multiprocessing (SMP) system and 10GB of storage to eight nodes per cabinet. Each node can contain a minimum of 2 processors and a maximum of 32 processors, and memory can be as little as 1GB per server (upgradeable to 4GB per server).
The architecture provides flexible configurations for a variety of thin-client solutions. NCR provides tools such as SMP Manager (so you can prioritize the processor user) and Master Minder (which lets administrators manage applications via rules and thresholds). Neither of these programs provides dynamic load balancing when both systems are online, but they can adjust when one server fails.
My only concern about the WorldMark 4300 is that NCR encourages using round-robin Domain Name System (DNS) or LifeKeeper's IP addressing rather than dynamic load balancing. Round-robin DNS comes native with Terminal Server, and LifeKeeper protected IP addressing is included in the base LifeKeeper software. But these provide only fault tolerance and not load balancing. You can install a copy of Citrix MetaFrame or Cubix Balanced Cluster Service on the WorldMark 4300, but I was disappointed that NCR didn't include either of them with the system I received.
Marking the Path to Thin Clients
The WorldMark 4300 is a compelling solution for providing fault-tolerant, Terminal Server capabilities to clients. The system I tested included everything you look for in a Terminal Server solution. However, implementing 4-way servers raises the WorldMark 4300's price and results in users placing their front-end and back-end applications on the same server. A server failure might reduce the performance of the surviving server.
Other solutions provide more flexibility using dual-processor systems, which you can flexibly configure. NCR is banking on its LifeKeeper solution, but in my opinion the company can enhance the base configuration by including Cubix's load-balancing solution, which offers a low-cost alternative to Citrix MetaFrame. The combination of LifeKeeper, Cubix Balanced Cluster Service, Terminal Server, and the WorldMark 4300 would form a resilient thin-client competitor.
|WorldMark 4300 Terminal Server|
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Four 200MHz Intel Pentium Pro processors with 512KB of cache per processor, 1GB Error-Correcting Code RAM, Quad Ultra SCSI channels, Integrated 10/100 Ethernet, 4.3GB hard disk