My understanding from being a member of the linux-raid list for eons is that if either the master or slave disk fails on a channel with 2 or more disks, you're almost certain to lose access to the entire channel. With SCSI it's a tossup, depending on the severity of the failure and the controller/firmware interactions.
What I would recommend is that folks that want IDE RAID use something like the 3WARE IDE hardware RAID controller. They're pretty cheap (~US$125 for 2 channels and ~$200 for 4 channels) and come in 2/4/8 port models...each having a dedicated channel for each disk. With a 2 channel card and a pair of cheap quantum 7200rpm 20.5gig disks striped as a RAID 0 device, I was able to get about 52mb/sec on reads and about 45mb/sec on writes using bonnie and 4X the physical RAM for the dataset. That's on a P3-733 with 256mb RAM and Redhat 6.2.
Cheers,
Chris
