Economies of scale

RLX Technologies' System 600ex Chassis, priced at $2,400, holds up to 10 of the company's server blades, and has high-speed connections and redundant power supplies.

Economies of scale

Interest grows in blade servers cut deployment, management costs

What's the big deal about blade servers? Think small: in the size of the servers, in the number of cables and wires cluttering up the back of a rack, in the time required for setup and management, and'in some cases at least'in the amount of power consumed.

At the simplest level, blade servers are complete servers on a single card that plug into a rackmount chassis. They're hot-swappable'just slide them into the chassis and they're up and running in seconds. Hundreds of blades can fit into a very small space.

Theirs is a different arrangement from what most of us are used to with servers. A typical six-foot server rack in use today holds up to 42 1U rackmount servers, each 1.75 inches high. Because each server requires its own power cables, Ethernet and Fibre Channel controllers, software management module and keyboard/video/
mouse switch, there's quite a bundle of cables, spare network interface cards, power sources and other paraphernalia to manage.

Blade servers promise to correct these problems, but will they deliver the goods?
A couple of new companies such as RLX Technologies Inc. and Egenera Inc., and some well-heeled computer manufacturers such as Dell Computer Corp., Hewlett-Packard Co., IBM Corp. and Sun Microsystems Inc., think they will.

Blade servers are cost-effective because they eliminate many of the complications of rackmount designs and pack a lot of computing power into small spaces. You need less technical expertise than with other servers, and they help eliminate the annoying cable clutter behind server racks.

There are different blade server designs'from dense, low-voltage models to high-performance, low-density versions. There also are a couple of proprietary, rack-optimized designs with some'though not all'of the features of blade servers.

Shared components

The term blade server typically refers to a proprietary chassis that can hold a number of hot-swappable blades that act as independent servers. For example, IBM's eServer BladeCenter is a 7U chassis that can hold up to 14 server blades for a total of up to 84 high-end servers in the rack.

What makes the blade server so efficient is that the chassis generally holds common components such as power supplies, fans, CD drives, Ethernet and Fibre Channel switches and system ports, all of which can be shared by the blades.

The server blades are smaller units that slide into the chassis' blade bay. As miniservers, they typically have one or two processors with associated RAM, one or two disk drives for storage and all the other components of servers'except for the common components built into the chassis.

Option blades, which may or may not come with a particular system, are generally shared by the server blades and provide additional features such as controllers for external I/O, or disk arrays or additional power supplies. Sun Microsystems' Sun Fire SSL Proxy Blade integrates accelerated Secure Sockets Layer encryption and decryption into the Sun Fire Blade platform.

Many processors

Blade servers use a fairly wide range of processors, from low-cost Pentium IIIs to high-performance Intel Xeons running at 2 GHz or faster. You should work closely with the vendor to determine which architecture and processors will be most efficient.

Blades with single, low-end processors can save users money on up-front costs and electrical bills if their workloads don't require lots of horsepower, such as for edge-of-network service like load balancing, firewalls or print and file serving, according to IBM.

For large, enterprise-class workloads, choose blade systems with high-end, dual chip sets'quads aren't yet generally available, though Hewlett-Packard just released the ProLiant BL40p series, too late for inclusion in the accompanying chart on Page 46. Prices for the quad systems range from $8,238 for a 1.5-GHz system to $18,268 for a 2-GHz system.

By most measurements, blade servers stack up well against other server architectures. Consider the following categories.

Scalability. Scaling a typical blade server generally involves little more than sliding a new blade into an open bay on the chassis. Via management software, the system configures it to the network, and boots from its own disk or from a network storage device. You can scale a blade server up or down without touching power, networking, serial or I/O cables.

Versatility. Advanced designs support a mix of blades with different types and speeds of processors. Enterprise workloads can be consolidated in one chassis, without the need for rackmount 1U servers and standalone servers to perform different functions.

High availability. Like conventional rackmount servers, blade servers include plenty of high-availability features such as redundant or hot-swappable components. But they take it a step further because the blades themselves can be hot-swapped. The more advanced servers can be designed so that there is no single point of failure.

Cost. Blade servers share power units, cabling, switches and other key components, resulting in lower initial and ongoing costs than other servers have. They generally use less power per CPU than standard servers, and can be running within minutes, saving technicians' time. They also require about half the floor space of rackmount servers.

Industry analysts are optimistic about blade servers' future, but I'd carefully ponder the following points before jumping on board:
  • To date, only a handful of manufacturers are shipping blade servers; it's difficult to make honest product comparisons or assess the potential success or failure of the new form factor. Manufacturers also have adopted different nomenclatures and widely different designs for their products.

  • Blade servers are proprietary, so you can't just stick one manufacturer's blade into another's chassis and make it work.

  • Check on how well a server's management software consolidates information from other network components.

J.B. Miles of Pahoa, Hawaii, writes about communications and computers. E-mail him at jbmiles@hawaii.rr.com.

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