RAIDing my wallet: the disk subsystem
The most expensive piece of the whole puzzle was the disk subsystem, which was the most troublesome part of our old server, and the one I was most determined to upgrade. I snagged an old version of Intel's SRCU31 SCSI RAID controller on eBay, and upgraded it to the latest firmware revision, which essentially transformed the unit into a like-new SRC31A with an entirely different driver and software architecture. (It took some work to determine that this upgrade was, in fact, possible. It seemed impressive at the time, anyhow.) I also ordered a 128MB DIMM to use with the controller, to give it a little more cache than the 32MB DIMM that came with it. However, the thing didn't seem to like higher density memory chips. Rather than push the issue, after seeing the effects of cache memory in our roundup of IDE RAID controllers, I decided we could live with the stock 32MB DIMM.

For drives, I picked Maxtor's Atlas 10K III. Five of them. Like so:

Our new RAID array poses for a photo

SCA connectors for easy hot-swappability

I set up these 17GB drives in a RAID 10 array with one drive acting as a dedicated hot spare. The total capacity is 34GB, or less than it would be for a RAID 5 array with the same number of drives. However, RAID 10 keeps the controller's i960 processor from having to handle the parity calculations necessary for RAID 5. Total disk capacity is really not a priority in this application. Performance is, and RAID 10 was the best choice for performance.

Oddly enough, I almost had to scrap the whole thing when the RAID controller card wouldn't fit into the case with a SCSI cable attached. The controller is a full-height PCI card, and it was plugged into a PCI riser that allows cards to be inserted parallel to the motherboard (this so things fit into a 2U enclosure). SCSI cables plug into the SRCU31 at the very top of the card, and the cable's connector, slightly but definitely, wouldn't clear the side wall of the case. I was able to overcome this problem by switching to a SCSI cable with a SCSI connector just a millimeter shorter, which allowed me to cram the card into the case. Crisis averted.

At the end of the day, this hardware setup promised solid reliability, but delivered something just as important: excellent Linux support. Red Hat 7.3 installed without needing additional drivers, and Intel's software suite offers full control over the RAID array from inside Linux. Have a look at the real-time statistics the software provides for each physical drive in the array:

Oooh.. graphs

Intel's Storcon utility allows one to configure an array, add or remove drives, check on the status of a degraded array, direct repairs, and the like. On a critical server in a remote location, this kind of capability is priceless.

Or at least fairly expensive.

Clean bill of health