I have a 2 drive raid with ST3500418AS Drives. I had a drive go bad so I put a Back up in and started a rebuild. I started the rebuiled in Thursday at 11:00 AM and as of today it is only at 75% complete. I really don't think it should take this long to rebuild and 500 gig HD.
It would be very nice to hear more about the software and hardware of your config.
1.5 hrs to re-build RAID1 on a 2/3 full pair of 500 GB drives is a nice performance - I am currently using a NSLU2 device and when I changed the backup drive, it took over 56 hours to do a disk 1 to disk 2 backup of about 568 GB.
(This is a 2004 era gadget that has 2 USB ports and 1 ethernet ports, it shares the contents of the USB drives over ethernet and can be configed - as I have done - where one drive gets a daily backup from the other, a cheap approximation to a true RAID1 system)
The performance of this thing sucks and I need to figure something new.