Building your own RAID.

Hardware
Hardware is highly dependent on the controller, but definitely the easiest to set up while offering the most options. Consult your manual! Remember, if pain persists, please see your Google.

Benchmarking
All tests were performed on an ASUS KFN32-SLI/SAS with dual Opteron 2218s and 1GB of registered Corsair RAM each, the last kindly supplied by Altech, for which we must say a big thanks! Four Seagate 250GB 7200.10 SATA 3Gb/s (ST3250620AS) hard drives were used for all tests, thanks to the wonderful Tina at Ingram Micro.

Unfortunately HDTach differentiates individual drives rather than volumes unless you use a hardware solution for RAID, so we’ve had to use SiSoft Sandra’s results for the Windows benchmarks, and for consistency have carried this on to the hardware benchmarks. Note that for NVIDIA’s RAID solution, it is actually using 0+1 instead of 1+0 – for efficiency’s sake we’ve plotted them on the same graph, as everything else uses 1+0.

On the hardware side we have the cards listed in the table to the right, each with eight SATA 3Gb/s ports.

Most of these aren’t toys, although you can spend more. If you look in the $100-500 range, then expect them to act pretty much as port extenders and nothing more. If you wish to run one of these cards under Linux, we suggest first checking the official driver support, then do a Google search to see if there are any issues with the card.

As you can see, the benefits of hardware cards start to kick in with the sequential writes in RAID 5, and this will likely improve even more once more drives are added. The Areca card seemed to have had compatibility issues, and although we updated the firmware and tried in three different boards, we still got the same odd results, with incredibly high access times and thus low random read scores.

Access times themselves were also all over the place, making the graph look like a two-year-old on Ritalin got hold of a crayon. You’ll note the cheap Highpoint controller actually does incredibly well across all graphs, and despite not having any memory, has done very well indeed in RAID 5 sequential writes.

Conclusion
There’s a RAID option for pretty much every level of budget – from the free software, through to cheap port extender cards, through to expensive cards with XOR engines. RAID makes a lot of sense, whether you just have sensitive data, need to set up a file server or are just tired of DVD-R’s amazingly short shelf life. If you have the cash to put into the hard drives, it’s definitely worth it.

Random Access Times

The cards we used