Specifically, I have a RAID 1 array configuration with two 500gb 7200rpm SATA drives mirrored as logical drive 1 (a) and two of the same mirrored as logical drive 2 (b). I'd like to add two 1tb 5400rpm drives in the same mirrored fashion as logical drive 3 (c). These drives will only serve as file storage with occasional but necessary access, and therefore, space is more important than speed.

In researching whether this configuration is doable, I've been told and have read that the array will only see the smallest drive size and slowest speed. However, my understanding is that as long as the pairs themselves aren't mixed (and in this case, they aren't) that the array should view and use all drives at their actual speed and size.

I'd like to be sure before purchasing the additional drives. Insight anyone?