> This makes sense. I'm pretty sure that tests that I've run in the past > using bonnie++ or iozone showed faster reads with raid1 than with a > single drive. I would think that if the drives are on seperate > controllers (and depending upon the performance/capacity of the drives > and controllers), there could be notable improvements. > with SATA or SAS, of course, every drive is on its own channel. even with PATA, at 100 or 133Mbyte/sec, only the fastest newer drives would saturate the bus doing two transfers concurrently. now, after i wrote what I did above, I dug up the kernel.org 2.6.18 kernel that RHEL/CentOS 5 is based on, and it still had the older code sequence as shown in that 'to do' list entry... but I didn't run the RHEL patch sequences against it, its quite possible RHEL retrofitted this patch to it.