Server Partitioning

Server partitioning offers a number of distinct advantages to information technology departments. For one thing, it allows systems administrators to consolidate multiple applications into one physical server box, which helps to centralize management, save space and potentially lower administrative and management costs.

Partitioning is also advantageous in multitier application environments, such as enterprise resource planning or data warehousing, where the applications are often functionally divided across multiple desktop clients, application servers and database servers.

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Partitioning technologies allow administrators to host these applications on different partitions within a single server, thereby improving performance.

Implementations of partitioning -- and even its definitions -- vary widely among computer hardware vendors.

Let's Get Physical

Some vendors implement physical partitions, where resources are divided along hardware boundaries. Others use a more software-oriented -- or logical partitioning -- approach. And some use a bit of both.

Physical partitioning involves the ability to take a single large server and divide it into multiple smaller systems, with each partition running its own copy of the operating system. Each partition acts as a physically independent, self-contained server with its own processors, memory, input/ output subsystem and network resources.

The boundaries can be reset at any time. This once required users to bring the system down, but it can now be done while the network is running.

Is This Logical?

Software-based, or logical, partitions are more flexible because the boundaries between them aren't physically defined. In theory, at least, a single processor can be divided among multiple logical partitions, or resources such as memory and disks can be shared dynamically between partitions.

This flexibility allows applications to maximize the use of total system resources as needed instead of being confined by physical boundaries.

Partitioning technology has been around for a long time in the mainframe space, but it started to gain attention in the distributed client/server arena only in the past two years or so. The trend toward server consolidation has driven much of that interest.

"Companies are trying to recentralize their servers because they are finding it hard to manage their servers," says Tony Iams, an analyst at D. H. Brown Associates Inc., in Port Chester, N.Y.

"IT organizations are trying to reorganize how they manage their resources and are, to a certain extent, trying to undo the distributed-server deployments" of previous years, says Jean S. Bozman, a server analyst at International Data Corp. in Mountain View, Calif.

Partitioning allows companies to consolidate the work previously done by multiple independent servers, including different types of workloads, onto a single server, Bozman adds.

The highest level of sophistication has been achieved by IBM with the logical partitioning (LPAR) technology found on its System 390 mainframes, Iams says.

Sun Microsystems Inc. has been a leader among Unix system vendors in driving the use of partitioning technologies in distributed computing. The company's Dynamic Systems Domain capability combines hardware- and software-based techniques to help administrators partition high-end E10000 systems into 16 separate segments.

Sun's technology allows systems administrators to automate the process for resetting partition boundaries and reallocating resources as necessary.

Another example is IBM's midrange AS/400 server, which uses an adapted version of LPAR technology to offer a similar capability.

Dynamic Partitioning

Compaq Computer Corp. is preparing to launch later this year a new Unix server that will offer dynamic hardware partitioning for workload management and server consolidation. Users will be able to create, resize or delete partitions without rebooting.

Such features will allow administrators to quickly allocate additional resources to applications -- say, to handle a sudden spike in Web server traffic -- without serious disruptions.

Other vendors offering Unix partitioning capabilities include Unisys Corp. in Blue Bell, Pa., and Sequent Computer Systems Inc., an IBM subsidiary in Beaverton, Ore.

Both companies offer partitioning capabilities that allow administrators to run different operating systems within the same box -- for instance, with Windows NT running on one partition and Unix running on another.

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Copyright © 2000 IDG Communications, Inc.

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