Kmart shines its Blue Light on solid state disks

When Kmart relaunched its Blue Light Special this year, the company needed a high-speed storage technology to handle the load of its outbound e-mail and targeted mailing to customers.

Kmart chose solid state disk technology from Imperial Technology, which speeds up mail delivery by caching the large, frequently used files in solid state memory.

Solid state disk technology is used by many Web sites, such as Yahoo and eBay, to store frequently used files such as e-mail message queues, database logs or transactions, which are too large and too slow to read from conventional disk. Data transfer suffers from an imbalance between the speed of the CPU and the slow nature of disk drives.

With solid state technology, those files that are used most often are stored on the solid state disk where they are instantly available. The remaining data -- the messages themselves -- are stored on a conventional disk, speeding up a part of the process that is critical to operations., Kmart's e-commerce site, lets users shop on the Web but also serves lots of data -- such as the targeted mailing campaigns Kmart sends to its customers.

Once Kmart has collected the name of a buyer and analyzed his purchase or interest, the company can send mailings to that user based on personal preferences and previous purchases. For instance, if a shopper buys a fishing pole online, Kmart might want to update him via e-mail when hooks or bait goes on sale.

San Francisco-based uses solid state technology specifically designed to handle large volumes of data and move it to users more quickly. The Web site handled 8.5 million unique users during the November and December 2000 holiday season, according to Media Metrix, an Internet media measurement service.

The network consists of a Solaris server that merges mail as it comes in from the Internet and hands it off to a data-mining application on a back-end Compaq ProLiant 8500 server. The data-mining application analyzes individual mail messages, shopper history and information requests and lets Kmart decide which type of targeted mailing to send the customer.

From there, a mailing can be generated that fits the user's profile. That mail is passed to two Solaris 420R workstations equipped with a solid state disk. The Solaris 420Rs are clustered for redundancy, and a 2G-byte solid state disk is shared by each of the 420Rs. If one 420R fails, the other takes over.

Individual mail messages are stored on the 420Rs; the message queue is cached on the solid state disk. Mail is then passed back out to the Internet as fast as 150,000 per hour. All of's equipment is colocated at a data center elsewhere in San Francisco.'s uses SendMail as its mailing software. Like many mail systems, where messages are stored on disk and need to be retrieved, SendMail is very disk I/O-intensive, says Jonathan Loran, senior network administrator with

"In order to accelerate the [SendMail] application, we went with a solid state disk instead of using hard disk. We put the active mail queue on solid state disk," he says.

According to Imperial, the solid state disk is designed to send out 250,000 mail messages an hour. The solid state disk operates at least 100 times faster than server hard disks, the company says.

Solid Data also makes solid state disks, but Kmart did not evaluate other vendors for this implementation.

Solid state disk technology is expensive but worth it for many users. In the case of Loran at, spending that much money to speed up e-mail processing is essential. A 4G-byte solid state drive can cost as much as $65,000.

This story, "Kmart shines its Blue Light on solid state disks" was originally published by Network World.

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