What you propose isn't different from copying/cloning to an external drive, then back again, however, there are some technicalities on the controller to be aware of: When you remove drive 3, the controller will want to fix the degraded RAID 1, so there is a possibility that when you insert the larger drive in slot 2 that it will try to rebuild it into the existing 146GB RAID 1 ... if so, you will need to stop it.  There is also a possibility that the drive will show as Foreign ... if so, you need to Clear it first (OMSA, Storage, PERC, Information/Configuration, Foreign/Clear).  Once Ready, you will need to create a new Virtual Disk - a single-disk RAID 0.  You can then copy/clone data from the 146GB RAID 1 to the new 300GB RAID 0.  Once complete, you will need to remove drive 2 and delete that RAID 1 Virtual Disk.  Once complete, then you will need to insert the other 300GB drive (again making sure it shows as Ready), then "reconfigure" (OMSA, Storage, PERC, Virtual Disks, RAID 0, Reconfigure) the single-disk RAID 0 to a two-disk RAID 1.  Done.
This machine has (4) 2.5 inch drive slots - current config is:  drive 0 and 1 - raid 1, 36GB - Windows drive "c" drive 2 and 3 - raid 1, 136GB - Windows drive "d"  I need to increase the capacity of the "d" drive - is there anyway to break the mirror (keeping the D drive accessible), and remove the extra 136GB drive, replace with a 300GB drive as a new drive letter, move the data over to it, remove the "d" drive,  change the new "e" drive to the "d" drive, add another 300GB drive, and mirror them - is this even remotely possible?  thanks  danny
Adding space on PE1950 w\Perc i