I have a server with 2x 73gb SCSI in a mirror raid. I'm going to drop a third drive in there (1RU, max of 3 drives). Now I know if I mix a 15K and 10K in a raid the I/O of the 15K drive is limited to that of the 10K drive.
In this case I have...
73gb 15K / 73gb 15K (Mirror)
146gb 10K (Backup)
Will the two 73gb raided drives be stepped down to the speed of the 10K?
What type of RAID controller? Typically to implement this you'll see a RAID 1 Virtual Disk (your Mirror) and a RAID 0 Virtual Disk (containing just your 10K drive), this should not have any negative performance on your existing RAID 1 array - depending on the type of controller.