Midrange Stuff, OS/400 Edition

International logistics operator Kuehne & Nagel is the first OS/400 shop to report exceptional results using a relatively new data caching technology to speed high availability replication across a WAN. The $6.7 billion Swiss corporation managed to stave off purchasing two additional T-1 lines to connect its primary and backup OS/400 servers in the United States and Canada by installing Expand Networks' data caching devices. K&N reports that these devices compressed its OS/400 replication stream by 500 percent, and now it has bandwidth for other applications.

K&N is one of the largest logistics companies in the world, with 18,000 employees at 600 locations in 96 countries. It transports freight by air, land, and sea, and lends its expertise in supply chain management and integrated logistics to its customers. In North America, K&N relies on DCS Transport and Logistics Solutions' supply chain application, Computer Integrated External Logistics (CIEL), running on OS/400 servers.

The global nature of K&N's business requires it to support operations 24 hours a day, 365 days a year, so four years ago the company purchased DataMirror's High Availability Suite to replicate data and objects between its AS/400s. The company purchased two dedicated T-1 lines, which carry about 1.5 Mbps each, to ferry the company's replicated data from one place to another.

Maintaining enough bandwidth is a crucial factor in high availability environments. With tens of thousands of objects constantly being replicated between K&N's OS/400 servers, any acceleration in the pace of business could spell trouble. "At month's end, we would build up so many journals that we couldn't get through. It would set us behind a day, a day-and-a-half," says Norman Berger, IT director for K&N. "With high availability environments, it's bandwidth, bandwidth, bandwidth. If you get behind the mirror, you're dead."

This 3 Mbps of bandwidth was sufficient for K&N's operations for some time. But the company's bandwidth needs increased dramatically in the last year after the consolidation of its Canadian operations on a new iSeries Model 890, running at a datacenter in Connecticut. Because of the load this consolidation added to the DataMirror replication system, Berger projected that the company would need to purchase two additional T-1 lines--at a total cost of well over $100,000 per year--to provide sufficient bandwidth between the Connecticut data center and its backup AS/400 server, located at a SunGard disaster-recovery center in Pennsylvania.

One of K&N's infrastructure vendors had heard about a product from Roseland, New Jersey, based Expand Networks that was claiming extraordinary compression rates on IP traffic. Expand's IP ACCELERATOR family, which began shipping in quantity in 2001, uses a patented algorithm to detect patterns in IP traffic at the byte-level. Instead of transmitting the entirety of these repetitious byte-level patterns, the device caches the pattern in memory and sends a short identifier that points the pattern to the other ACCELERATOR device on the other side of the network, which then reinserts it in the datastream. About every 30 minutes, the devices automatically update their caches with the most recent patter, and with this technique Expand regularly records 100-to-400 percent improvements in bandwidth over IP networks.

Expand's product family costs far less than dedicated T-1 lines, partial T-3s, or even satellite-based connections, which are popular with Expand's government clients. The IP ACCELRATOR family ranges in cost from about $2,000 (for the 1800 Series, which supports up to 128 Kbps) to $45,000 (for the 6800 Series, which can carry 45 Mbps). Berger opted to try a pair of 4800 Series devices, which come with a price tag of $10,000 to $14,000 each and can support up to 6 Mbps. If the devices were successful in accelerating K&N's data anywhere close to what Expand was claiming, it would mean avoiding the purchase of additional T-1 lines.

But Berger didn't get a 400 percent improvement. When he hooked the IP ACCELRATORS up to his WAN, Berger saw that the devices were actually accelerating his DataMirror traffic by up to 500 percent. "I'm thrilled," Berger says. "This thing burst up to 5.25 Mbps throughput on 1.5 Mbps of real bandwidth. It works really well."

K&N is now able to get almost as much usable bandwidth out of one T-1 line with the IP ACCELERATORS as it could with four T-1s without the acceleration. However, Berger plans to keep both T-1s, for the same reason the company has two AS/400s: redundancy.

So why did K&N achieve such good compression results with the DataMirror replication? It certainly wasn't that Expand built its devices with the iSeries and its proprietary character code in mind. Expand's vice president of business development, Ariel Shulman, says the IP ACCELERATOR technology works on any data that can be sent in an IP packet. "We don't know too much about AS/400s," Shoman says. "But our box has no direct interaction with the AS/400, [and] EBCDIC does not provide any limitations."

Glen Sakuth, DataMirror's director of development, says K&N's high rate of compression could be explained by the peculiar characteristics of OS/400 objects. "It's somewhat logical in a lot of respects. There are definite patterns in a lot of the objects," Sakuth says. "Because of the nature of the data that goes across in a high availability environment, it's a solution that works extremely well there."

The OS/400 objects "may just fit the algorithm that Expand has," Berger says. Berger remembers getting decent compression on SNA datastreams using old IBM 3780 terminals. "This is better than that. If you watch it for a while, it actually learns what's coming down the pipe. It learns by itself."

Berger is also testing the IP ACCELERATORS against other kinds of network traffic, including IBM Lotus Notes, Internet, 5250, and printing traffic. On these types of traffic, Berger reports about 2.5 times improvement in bandwidth. "The jury is still out on 5250," he says. "The network is oversubscribed, so the data doesn't accelerate as well." However, some of K&N's branch managers are seeing improvement in 5250 screen response times. "They can see immediately that the screens are coming much faster."

As far as other OS/400 high availability environments, Expand's technology should work equally well. Berger reports that his Expand technician told him the devices have also been installed at a company using MIMIX, the OS/400 high availability software sold by Lakeview Technology. Sakuth says there's no reason why this technology wouldn't work with other vendors' OS/400 high availability software.

In fact, Expand's IP data caching technology could benefit a good percentage of shops using OS/400 high availability software. Sakuth estimates that about 30 percent of DataMirror's customers were constrained by limited bandwidth to one degree or another. Bandwidth constraint is a fact of life for OS/400 shops replicating large amounts of data over distances greater than 10 miles. It's why one of the first things done in a high availability implementation is to go through and remove certain types of unnecessary files from the replication process, such as temporary files and maybe development files. Even after these things are taken care of, bandwidth is (and Bill Gates would agree with this) a lot like money: You can never have too much.

As for the high rate of compression found on K&N's OS/400 object replication, DataMirror will be conducting additional tests in the lab to better understand the mechanism, Sakuth says.