I have always avoided the promise fasttrak cards for exactly that reason ("hardware" being in quotes). It's my understanding that they're not much more than their udma cards with drivers that do most of the RAIDing.
Actually, Promise is one of the very few companies that are doing something innovative in RAID... Their hardware is not 100% software RAID nor 100% hardware RAID. They instead follow the model of network cards -- perform all key operations on the board, and let the host CPU handle the rest.
It was also my understanding that the 3ware cards are true hardware raid and are up to the task of something like this, which would also explain why they're 4x the cost.
Correct.
I am looking at a four disk raid5 or raid10, and it seems like the interrupt load from four drives on four channels might be a bit excesive. I'm going to be running critical services on the machine that the drives are in (namely mysql and nfs) and don't want to worry about performance.
Once your spindles can max out your PCI bus bandwidth, -then- you can start worrying about PCI bandwidth and interrupt load ;-)
Jeff
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