I have two 180G Firewire 800 drives that used to be my back up pair (back when everything would fit on that). Since the 24 inch iMac has one Firewire 800 port I thought it might be interesting to see if there is anything to be gained daisy-chaining them and setting them up as a striped RAID set.

I partitioned each drive into ten partitions. This let me pick the first and last partitions for testing: the first being the fastest (closest to the edge of the disk) and the last being the slowest (closest to the center). Then I ran three disk speed tests with XBench.

Single first and Single last tested just one partition on one drive. Striped first tested the first partition on each drive striped. Striped last tested the last partition on each drive striped. Mirrored first tested the first partition on each drive mirrored. Mirrored last tested the last partition on each drive mirrored. For comparison I also included the results from the internal 750G SATA drive and a single Firewire 400 drive. Here are the results in Mbytes per second for 256K transfers and a 32K RAID segment size.

With a 256K RAID segment size I tried a few more tests. I took three very large files totaling 9.89GB and copied them from the internal hard drive to the striped RAID pair, then copied them back to the internal hard drive, then duplicated them on the RAID.

I think this RAID set up will be useful if I need a scratch disk, particularly if the processing that is occurring is reading from one disk and writing to another.

Tags: iMac, RAID, Firewire, Interesting Stuff