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Internal 4-Way SATA RAID For The XPC     A Concept Study
(Review by MS, April 20, 2003)

When we originally looked at the Shuttle SB52G2, one item very high on our wish list was to get rid of the floppy drive. Well it is not quite that simple, anybody can get rid of the floppy but what we had in mind was rather to replace the floppy with a 4-disk internal RAID. Again, it is not that simple either, since we also needed to sacrifice the 3.5" standard HDD. But then, leaving out the FDD and the HDD gave us enough room to fit a total of eight 2.5" SATA HDDs into the same real estate.

Unfortunately, though, we did not have eight drives, we did, however, have four 2.5" Fujitsu SATA drives that we hooked up to a Promise FastTrack S150 TX4 four port SATA controller card and used the rest of the unused space for luxurious ventilation.

We started out with a proof of concept approach with a preproduction controller card, BIOS and drivers. We then worked our way up to the production version of the firmware and drivers. In retrospect, hindsight has always 20/20 vision but the results for both a 4 disk RAID 0 and a RAID 01 (striped and mirrored across 4 drives) are notable enough. We further used the opportunity to look into a few of the most common drive benchmarks to reveal what they show, or rather, what they don't show.

Depending on screen resolution, this picture is about real life-size and shows one of the 2.5" Fujitsu SATA drives in the protective antistatic bag. For reference, the little pouch is less than 3" across.

Needless to say that any overgrown XPC simply defies the purpose of the concept already; in other words, there needs to be another solution for the problem. Think long, think hard, and by the end of the day, the solution is very simple: Bigger is not always better, regardless of what the viagra ads are trying to tell us!

If you cannot make the enclosure any larger, you have to make the ingredients a bit smaller. Since what we are talking about here are hard disk drives, the solution already has a precedent in the form of laptop drives in 2.5" form factor and slimmer than Twiggy .... but that was about 35 years ago when a hard disk drive of e.g. 40 GB would have easily outweighed Twiggy or Jane Mansfield (on the other end of the spectrum). Laptop drives are also using a different interface than standard IDE drives and even though it is possible to mod the connectors to retrofit laptop drives to a standard UATA interface, it would be a clumsy solution at best.

The latest addition to the storage world is Serial ATA and one of the not yet so overt advantages of the new format is the reduced size of the connectors, making the new interface ideally suited for smaller hard disk drives like, for example the above mentioned 2.5" format. Even 3.5" Serial ATA drives are still somewhat hard to come by, at least from the big players in the field, 2.5" drives are almost non-existent or so it appears. On the other hand, one can only look for something one knows that it exists.

Anyway, the result of our (very short) search unearthed the fact that Fujitsu has the drives we were looking for. Unfortunately, as it turned out, those adapted laptop drives are running at 4200 rpm only and furthermore only feature a 512 kB disk cache. Keep in mind, though, that those are first generation Micro SATA drives and if four of them are bundled together, the overall performance was still expected to sky-rocket or else provide some healthy redundancy. Moreover, even four of these drives comfortably fit into the plam of my hand.

The next problem we encountered in the realization of our project was the fact that, at the time, there were no interface cards featuring 4 x SATA ports. The first card on the market to fully support quad-SATA, that is, the Promise FastTrak S150 TX4, just hit the market and appeared to be the right toy for our setup. Just as a reminder, what we have in mind is merely a proof of concept for the time being, sort of a look into what maybe one or two years down the road will be THE platform.

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