Datacenter Server

Datacenter Server

Can Datacenter Server scale the heights of network computing?

by Barry Nance

Microsoft Windows operating systems are nearly as
common as keyboards in desktop computing, but the server versions of Windows lag significantly behind such OSes as SunSoft Solaris in the management of database, Web, file sharing and application server machines.

With a new version of Windows that's more fault tolerant and scalable than its predecessors, Microsoft Corp. is aiming to attract network managers who traditionally have gravitated toward some form of Unix for data-intensive back-office computing tasks.

Setting up and scheduling Windows
programs to run as jobs is a simple process in Datacenter Server.

Windows 2000 Datacenter Server can use up to 32 processors and support four-node clustering. Beta 2 of the server OS was released May 23, but the final product will only be available bundled with Microsoft-approved hardware.

Microsoft says a cluster of computers running Datacenter Server can compensate for a hardware failure in one computer because the others in the cluster will pick up the workload.

Datacenter also can provide significantly more memory for running applications, access disk data in a storage area network more quickly, and treat computer programs as jobs to be scheduled and monitored.

A rundown of Datacenter's significant features:

Clustering and fault tolerance

In a cluster of machines, the OS' Network Load Balancing feature detects a server failure within 10 seconds. To pick up the computing workload, NLB automatically reconfigures the cluster by directing network traffic to the remaining healthy servers.

Once a failed server is repaired and brought back online, NLB transparently rejoins the server to the cluster. Managers using the failed machine as a file server, however, will likely have to log in again to the server after it's fixed. More important, NLB might not replicate data among the clustered computers. This means, for example, that updates to a database on a failed machine will be lost if you haven't configured the database's replication feature.

SMP and scalability

Hardware and software vendors would have you believe that a computer with multiple processors and network adapters is highly scalable. If you can put more processors in a computer, they say, it's more scalable. An eight-way symmetric multiprocessing machine thus is more scalable than a computer with only one or two processors.

In the same vein, an operating system that can concurrently run eight computer programs on an eight-way SMP machine is considered more scalable than an operating system that can manage only two processors. Microsoft deems Windows Datacenter Server scalable because it helps applications take advantage of up to 32 processors.

Technically, that's true, but it's only part of the story. By focusing too narrowly on technology, that perspective sidesteps the reality of how federal agencies and departments, not to mention businesses, deploy and use computers.

Scalability more accurately is a measure of how well both small and large workgroups can run the same application simply by adding computing resources for the large groups. A small workgroup can accommodate growth by obtaining more of the same application software, operating system software and computing hardware it already uses.

The real key to scalability lies in an application's ability to gracefully adapt to and utilize whatever computing resources you give it. The number of CPUs in each computer is only a small part of that equation.

Physical Address Extension

Realizing that accessing memory is faster than accessing hard drives, Microsoft has boosted performance by engineering Datacenter to use up to 64G of physical memory in a computer. Probably only a handful of applications will ever take advantage of this feature, but they'll be database or other data-focused products that use the memory to recall frequently used data.

Winsock Direct

Accessing data on a storage area network is a matter of sending request messages to the SAN and processing the resulting response messages. To make accessing the SAN data quicker, Datacenter includes network driver software specially designed for sending and receiving SAN data messages. Called Winsock Direct, the driver software bypasses a great deal of the usual TCP/IP protocol stack to shuttle SAN messages back and forth.

Process Control

The new Process Control tool lets you treat PC programs as if they were mainframe jobs. Not only can you schedule these jobs but you also can limit the amount of memory and CPU resources the jobs consume. ''''

In contrast to setting up mainframe CPU time and memory restrictions via the punch-card-
oriented Job Control Language, the graphical Windows interface simplifies configuring and scheduling of jobs.

Datacenter Server licensing

Microsoft has announced a licensing scheme for Datacenter Server that's considerably more restrictive than those of other Windows versions.

The initial investment aside, the fact that you cannot install Datacenter on different computers from a single CD-ROM disk will make network administrators' lives more complicated. Buying Datacenter also will require a close relationship with your hardware supplier because you'll get operating system patches and updates through subscription services the supplier offers.

Barry Nance, a software developer and consultant for 29 years, is the author of Introduction to Networking, 4th Edition and Client/Server LAN Programming. E-mail him at

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