InfiBand breaks server bottleneck

For many large organizations, it’s not the CPU that’s the bottleneck on server performance. It’s the I/O subsystem. Often there’s just no way to squeeze all the data a server’s applications need from disk to CPU and back again.

There are several attempts on the drawing board to boost system I/O. Storage area networks, or SANs, have gotten a lot of press. Most SANs today run over a transport called Fibre Channel, which provides a separate switched infrastructure between servers and storage devices. More recently, vendors have been developing iSCSI, a standard way of sending the SCSI storage protocol over IP networks. A company called Nishan Systems even provides IP storage switches that support both Fibre Channel and iSCSI connections.

Each approach has its advantages and disadvantages. All share one common disadvantage: When data arrives at the server, it’s limited by the speed of the 133MHz PCI bus to 1 gigabit per second–admittedly nothing to sneeze at, but slower than the rest of the storage infrastructure can go.

InfiniBand is a new technology that does away with the concept of an I/O bus. Instead, it offers a point-to-point switched I/O fabric between a host channel adapter on the server and a target channel adapter on the storage device. A single InfiniBand link operates at 2.5 gigabits per second in a single direction, while a bidirectional link has twice that rated capability. While real-world traffic will fall short of the rated throughput, it should be a significant fraction thereof. By adding multiple channels, vendors can build a really obese pipe between storage and CPU resources.

The end node devices can be interconnected by cascaded switches. That gives InfiniBand the ability to scale from a single server up to a system of a much larger scope.

InfiniBand’s Progenitors were two earlier groups: Next-Generation I/O, put forth by Intel, Microsoft, and Sun; and Future I/O, supported by Compaq, IBM, and Hewlett-Packard. Rather than compete, the two camps decided to unite as the InfiniBand Trade Association to fight the I/O bottleneck, and thereby make the resulting products more appealing to the entire industry.

The initial spec for InfiniBand was released late last year. This year, vendors have been building prototypes and running them together in interoperability tests, including a recent multivendor Plugfest. According to Alisa Nessler, CEO of Lane 15 Software, an InfiniBand management software vendor, the Plugfest results were mostly positive.

If testing continues to go well, expect to see the first InfiniBand products available for sale early next year. Initially, they’ll be available only for high-end server and storage clusters, but as the technology becomes more popular and prices decline, expect InfiniBand to find its way into even departmental servers.

InfiniBand won’t replace Fibre Channel or iSCSI, but it’s a welcome additional alternative for filling bandwidth requirements. If you haven’t committed to either existing camp yet and you can afford to wait a year, keep your eye on InfiniBand.

Sound bytes

Back in college, my stereo was my baby. I used to buy it upgrades and enhancements, and worry about whether my total harmonic distortion was lower than my friends’.

Fast forward to 2001. I don’t use my stereo as often as I used to. I spend far more time playing around on my computer. I still like listening to music though. Luckily I’ve found some products that let you combine the power of your computer with the sound of your stereo.

While there are comparable products for the Macintosh, a PC sits in my home office, and therefore I concentrated on products for that platform.

The first step is to get music onto your computer. If you have a CD-ROM drive, you can pop an audio CD in it and listen to it through your stereo speakers. You can also copy music from the CD to your computer’s hard drive. In their native audio format, known as WAV, songs take up a lot of disk space, so most of the time you’ll want to copy the songs in a compressed format. The two most popular compression schemes are Windows Media Audio (WMA) and MP3 (which stands for MPEG Layer 3). As compressed, a typical song takes up a hair less than 1 megabyte of space for each minute in length — less than a tenth of the space a WAV file requires. You lose some fidelity in the compression process (slightly more with MP3 than WMA), but unless you’re a fairly finicky audiophile, you probably won’t be able to hear the difference.

You can go in the reverse direction too — move music from your PC to a CD-R or CD-RW disc with a CD-writing device that uses a laser to etch blank discs. CD-R discs will play in most home, car, and portable players, while CD-RW discs usually won’t, unless your player was made this year. However, you can rewrite a CD-RW disc, while after you’ve written to a CD-R disc, you can never change its contents. You need software to burn the discs, but that generally comes bundled with hardware. If yours is lacking, the Cadillac of CD audio tools is Roxio’s Easy CD Creator 5 Platinum. With it, you can not only create discs that play both WAV and MP3 files; you can also back up your hard drive onto data discs.

If you don’t have the latest CD from your favorite artist at your desk, you may be able to download songs from it from the Internet. Napster, which once excelled at sharing songs, is now a shell of its former self. Other music sharing services are going strong though. Many are built on a software framework called Gnutella. My favorite Gnutella client is LimeWire. Download the free client, enter a song or artist name, and if another user on the Gnutella network has a copy on his hard drive, you can download a copy of the song you searched for. Be warned though, that it can take a long time to download the file unless you have a DSL or cable modem link to the Internet, and songs don’t download anywhere near as fast as a Web page.

Once you get a large number of audio files, organizing them becomes a bit of a chore. Two excellent programs for managing your digital music are Real Networks’ Real Jukebox and MusicMatch Jukebox. Even better is the fact that both are free (though both also have higher-end siblings with extra features you can pay for). Both let you organize your music files and create playlists, which specify the order of your songs.

Having music on your PC is handy, but what if you have a life away from your desk? You’ll want to take your music with you. If portability is your aim, it’s hard to do better than Sonicblue’s Rio Volt player. Rio Volt looks like a CD Walkman, but it can also play CD-R and CD-RW discs that you record yourself. Those do-it-yourself discs can include either regular audio files or your compressed MP3 files. Because a CD-R or CD-RW disc can hold 650 megabytes of data, you can carry around more than 11 hours of music on a single disc. Sonicblue bundles copies of Easy CD Creator 4 and Real Jukebox with its player.

Unfortunately, the Rio Volt doesn’t read or understand MP3 playlists, so you need to burn songs onto your CDs in the proper order.

Other good portable CD-R/CD-RW/MP3 players includes Philips’ eXpanium and Aiwa America’s XP-MP3.

Portable devices don’t recognize file names the way computers do, but you can select individual tracks or playlists if you make sure they’re labeled with what are called ID3 tags. These tags let you store the artist, song title, album title, and other information within the MP3 file. If you record music on your computer from your CDs, your recording program usually grabs these tags automatically from the CD or from an Internet database of CDs called CDDB.com. If you’ve copied the files from Napster or another source, your songs’ ID3 tags may be incorrect or absent. You can fill them in quickly using a free tool called MP Tagger.

Perhaps the best way to listen to digital audio is to play it on your home stereo system. Unfortunately, regular CD players won’t play CD-RW discs. Marantz’s $250 CD5000 CD player will, but it can’t handle MP3 files. To play them, you can turn to ReQuest Multimedia’s AudioReQuest Pro 40, which plays everything from music CDs to CD-RW discs. The AudioReQuest looks like a stylish black stereo component, but it’s really a computer with a 40GB internal hard drive — big enough to hold 275 hours of MP3 music recorded at the highest quality level. Unfortunately, at $2,500, the AudioReQuest is priced like a computer too.

If you don’t want to buy a second PC for your digital audio, you can try Voyetra Turtle Beach’s $100 SonicLink. The product includes of a wireless transmitter that hooks up to your PC sound card’s speaker output jack (with a Y cable so you can still listen to music through your computer’s speakers) and a receiver that plugs in to the auxiliary input of your stereo receiver. You also get a wireless radio frequency (RF) remote control that sends signal to an RF base station attached to a serial port of your computer. With it, you can play songs using the bundled AudioStation software on the PC. Because it uses radio waves instead of infrared, you can use the remote control from any room in the house, and you can easily program it to control your TV and three other electronic components too.

SonicLink is conceptually one of the coolest products I tested. I was pretty disappointed, however, that the sound quality at the receiving end was so poor. It sounded like music transmitted over a cordless telephone — not surprising, perhaps, as SonicLink uses the same 2.4GHz band that newer cordless phones use.

After testing so many digital audio products, I emerged from my basement to discover my children had grown and my plants had died. The moral: a good sound system is nice, but it’s only rock ‘n’ roll.

If you want to know more about digital audio, a good place to start is About.com.