Moore’s law for processor speed has a SCSI corollary: each new version is twice as fast as the last one. Adaptec’s PowerDomain 39160 is the first Mac card to support the new Ultra 3 Wide SCSI standard, with blazing 160-MBps performance, double the maximum 80 MBps of Ultra 2 Wide SCSI. And because the card has two Ultra 3 Wide SCSI buses, its total potential throughput is 320 MBps. But the card is expensive, and drive selection is limited.
Ultra 3 and Ultra 2 both use
(LVD) technology, which permits use of longer cables (up to 12 meters) in addition to providing faster throughput than earlier SCSI versions. However, if you add an older, non-LVD device (pre-Ultra 2 Wide SCSI), the speed drops to 40 MBps and you’re limited to 2-meter cables. Fortunately, with the PowerDomain’s dual-bus design, you can put older devices on one bus and reserve the other for faster Ultra 2 and Ultra 3 devices. Each bus has an internal and an external connector.
Macworld Lab tested the card on a Power Mac G3/400 with four Quantum Atlas Ultra 3 Wide drives. We performed the tests with all four drives attached to one internal port, and then with two drives on each internal port. The result? The PowerDomain 39160 is fast, but it does not reach the standard’s full 160-MBps potential. Using both buses, maximum read speed was 94.7 MBps and maximum write speed was 53.5 MBps. However, this is still about 1.5 times faster than Ultra 2 Wide SCSI (see “Fastest SCSI”).
The card doesn’t include any drive-formatting software. For single drives you use Apple’s Drive Setup; to set up a RAID array you’ll need third-party software.
Macworld’s Buying Advice
The PowerDomain 39160 offers fast performance, but it also sells for up to $400 more than a plain SCSI card. If you need the fastest possible throughput and are willing to invest in Ultra 2 or Ultra 3 drives, the PowerDomain 39160 is a compelling option. However, the card is costly overkill if you just need to connect a few Narrow SCSI devices.
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