So, I've been in RAID hell for a couple of days. It all started when my friend bought a Gtech ES for his Mac Pro. I got jealous and bought the budget equivalent, the Lacie Biggest Quadra 2 TB. I installed it with a Sonnet Tempo E4P eSata host adapter. I initialized the array set as a RAID 0 + 1. I have a PowerPC Quad g5 with 6.5 GB of Ram. I ran Xbench on the raid and got worse performance than any othe drive on my system! Internal HDD's, external USB HDD's and 500 GB software RAID. It's terrible! Not quite sure what to do. I tried doing a firmware update on the Sonnet to no avail. I'm totally lost, I spent the better part of the day trouble shooting, writing emails calling tech support etc. Please help.
If you want speed, then NEVER EVER use RAID 0+1. it must write to both disks, the same information.
If you want speed then use a real RAID 0 with at least 4 stripes. Each stripe adds about 60 MB/sec using SATA drives. If you want security, then RAID 0+1 is best. Actually, RAID 5 is most often used as a good compromise.