The Ethernet Alternative to USB Drives

USB is slower than promised, providing at most half the expected bandwidth (see The Truth About USB Speed). But the iMac, iBook, and Lombard PowerBook don't have any other option, do they?

Maybe.

Running daily backup on a network of 70-some Macs, I know backup over 10Base-T ethernet can hit 62 MB/min. - twice the best backup speed I've seen reported for a USB tape drive. (FYI, backing up over Ultra SCSI on a Blue G3/300 can break 1709 MB/min.)

Of course, performance varies by computer. The fastest backup is on G3 machines; the slowest on 68030-based Macs.

It got me thinking: Is a Mac on ethernet a viable alternative to USB hard drives?

I did some testing over 10Base-T ethernet to see what kind of throughput you can expect over a network. I copied 79 files (total of 5.2 MB) to three different Macs to see if network performance was in the USB ballpark. Here are the results. (Note that results might be faster with 100Base-T, which I don't have access to.)

Quadra 800, Mac OS 8.1, file sharing	125.8 MBps	1.0 Mbps
iMac Rev. B, Mac OS 8.6, file sharing	234.9 MBps	1.9 Mbps
Power Mac 7600/200, Mac OS 8.6, AppleShare IP	435.9 MBps	3.5 Mbps

Not quite as fast as USB - and far more expensive once we move to Power Macs with AppleShare IP. The least expensive alternative, a Quadra with an ethernet card, will probably set you back $100 to $200. You can drop a huge SCSI or IDE drive into it fairly cheaply, but it also requires a keyboard, mouse, and monitor. The whole setup can easily set you back $300-400.

On the other hand, it gives you a second Macintosh and a drive that can be shared on a network with as many Macs as you can put on the network. And you can set it up for Remote Access or as a shared internet connection for multiple computers. Network performance is about one-quarter that of a USB hard drive.

Switching to an iMac, we double throughput, but with a much higher price tag. You'll probably spend $800 for an iMac/233, then another $100-200 for a huge hard drive to replace what's inside. If you already have an iMac, you're probably better off putting that huge hard drive in the iMac you're already using.

The third choice is to run AppleShare IP, which offers nearly twice the performance of personal file sharing on the iMac. You'll want a 604-based Power Mac or clone (or better), which will cost $600 and up on the used market. Then spend $450 for a ten-user copy of AppleShare IP and add a huge ($200 or so) hard drive.

None of these are inexpensive solutions. Of those tested, only the AppleShare IP server offered the same performance as a USB hard drive.

On the other hard, all of these solutions provide a second computer and can be shared with an entire network. USB drives are attached to only one computer at a time, although it should be possible to share them over a network with File Sharing.

Conclusion

Is ethernet a viable alternative to a USB hard drive?

I can't speak conclusively, since I don't yet have a 100Base-T network to test, but it looks like it's not a cost effective alternative to a USB hard drive.

That said, the best way to find out for certain would be to connect USB drive to a Mac on a 100Base-T network and do further testing.

However, there are some benefits to networking even a slower, older Mac to an iMac, Blue G3, iBook, or Lombard PowerBook. The first is that you'd have a floppy drive, which you can use for making disk images to use on your newer Mac. With few exceptions, almost all installers work equally well from a disk image as from the original floppy. That could save you $100-180.

Another advantage of a second Mac is that it provides a second work station, letting others use a Mac while you're using the newer one.

But the biggest advantage is that as you add Macs, you already have a central place to store files for all your computers.

The biggest advantages of a USB hard drive are storage cost (IDE drives are far less costly per MB than SCSI drives) and plug-and-play portability.

Look for a follow-up in October, when I'll have access to a 100Base-T network.

Further Reading

• How fast is fast?, Dan Knight, Online Tech Journal, 7/19/99. Compares theoretical bandwidth of USB, SCSI, FireWire, and more.
• USB users may face bandwidth problems, InfoWorld, 6/8/98.
• USB compared to other ports, MacSpeedZone
• SCSI throughput, Mac Online Tech Journal. Historical overview of SCSI, including real world and theoretical throughput rates.
• Introduction to FireWire, Online Tech Journal.
• FireWire a form of SCSI, Alex Timbol, Online Tech Journal. Explains how FireWire grew out of the SCSI standard.