Question : RAID 1

I have a Dell Server with a PERC 6/i controller.  Originally I had 4 1TB drives where I created 2 1TB RAID 1 arrays.  The second Virtual Disk was for backup from the first which was partitioned into C & D drives.  I ended up with two 1.5TB drives from another server and hot swapped the backup drives one at a time.  The PERC rebuilt the RAID 1 and after both were swapped and rebuilt, the Server administrator showed 496 GB available on each drive.  I then created a third RAID-1 with the additional space and created another drive.  My question, is this a bad practice, having two separate RAID 1 on the same two physical disks?  Would it be better to back the whole thing up and rebuild the entire 1.5 TB as a RAID 1 and then partition it?

Answer : RAID 1

It's not considered "bad practice". As for performance, it wouldn't be much different than having a single RAID-1 with multiple partitions. The only drawback comes from trying to write data to partitions located on the same drive(s) simultaneously.