Compare and contrast
Before I go over each card we're looking at in detail, it's worth taking a quick look at a few similarities and differences. All the cards in this comparison support Windows NT, 2000, and XP right out of the box. Some actually support Windows 98 and ME, but those operating systems are probably not going to find their way into environments where RAID is really appropriate. The cards we're looking at today also all support at least one flavor of Linux, though they can't seem to agree on distributions.

This feature isn't advertised by some of the manufacturers, but all of the cards we're considering support multiple RAID arrays on a single card and different RAID levels between those multiple arrays. You can run a two-drive RAID 0 array right alongside a two-drive RAID 0 array if you want. All the cards also support hot spares if you want to configure an extra drive on the array to lie dormant, waiting to spring into action should disaster strike. Hot-swapping is also supported on all cards, though you'll need special hot-swap enclosures to get that feature working properly.

It's good to know that the cards share some common features, but what about where they differ?

Which levels of RAID are supported is probably the most important feature to look at when considering a RAID card, and there are a few key differences between the cards to note. 3ware's Escalade 7500 is the only RAID card to opt for a RAID 10 "striped mirrors" configuration over the more popular "mirrored stripes" RAID 0+1 setup favored by Adaptec, HighPoint, and Promise. HighPoint's RocketRAID 133 doesn't support RAID 5, and Promise leaves out JBOD ("Just A Bunch of Disks," for the uninitiated). We won't be covering JBOD arrays today, but we will explore RAID 5, even though HighPoint can't play there.

HighPoint's RocketRAID 133 is the only card in the lot that favors a two-channel configuration, which is probably why it's also the cheapest. The two-channel configuration supports four drives, but you're forced to run two drives per channel in a master/slave configuration. Each of the other cards supports only a single drive per channel and has four total channels of IDE goodness to spread around.

When it comes to PCI support, only Adaptec's 2400A and 3ware's Escalade 7500 aren't capable of using a 66MHz PCI bus, though the Escalade 7500 supports 64-bit/33MHz PCI modes. A high-performance RAID array does have a pretty good shot at maximizing the bandwidth available to 33MHz PCI slots, so it's good to see some of the cards supporting 66MHz bus speeds.

Drive interfacing is an interesting category to look at, not only because Adaptec's 2400A is the only RAID card in the bunch to run at only ATA/100 speeds, but because Promise's FastTrak SX4000 reads at ATA/133 speeds and writes at ATA/100 speeds. We'll explore what impact the disparity has on real-world performance a little later.

Things get even more interesting when you consider support for alternative operating systems. There isn't much agreement on which Linux distributions deserve support, but 3ware and HighPoint deserve bonus points for providing open source drivers for Linux. The FreeBSD support is also mixed, and 3ware resorts to directing users to an approved third-party driver rather than one of their own. Finally, for those folks out there that are into really alternative operating systems, Adaptec's 2400A is the only card that supports Novell's Netware.

Warranty-wise, 3ware and Adaptec have you covered for three years. Promise's warranty is two years, and HighPoint only covers you for one. A RAID card seems like something that would be upgraded less frequently than other PC components, especially since upgrades are likely to be driven by new hard drive technology that would require purchasing new drives. A two-year warranty feels a little short, and HighPoint's one year warranty seems unecessarily conservative.

Prices on the cards we'll be looking at today are all over the map, though the highest price doesn't necessarily guarantee the best or most current features. Adaptec's 2400A and Promise's FastTrak SX4000 both support expandable cache memory. Alhough Adaptec's card ships with its own memory module, you have to buy one separately for the FastTrak SX4000. The $183 price tag reflects the cost of the card itself and the 128MB PC100 ECC DIMM we used for testing ($26 for the DIMM, $157 for the card).

Update (18/09/2003): HighPoint recently increased the warranty period on all its products, including the RocketRAID133, to two years.