Multiple failing Seagate Barracuda ST32000542AS

Thanks for all the advice guys. Ive decided to replace the two failing Seagates, as Netgear recommend replacing any drive as soon as the reallocated sector count exceeds 50...

http://www.readynas.com/kb/faq/hardware/reallocated_sector_count_has_increased_in_the_last_day

Amazon have a good price on Seagate 3TB Drives (which are also on the HCL)
http://www.amazon.co.uk/Seagate-7200RPM ... 108&sr=1-1

I think I will order two of these, and then send the faulty 2TB ones back to Seagate. Then when I get refurbished ones, at least Ill have a couple of backup drives for use in an emergency.

One final question.. I ran a volume scan on the NAS (using the boot menu), and read that the results of the scan would be viewable in RAIDar
Running RAIDar (on mac), I cant find any way of seeing the results of the scan.

When I check the logs in FrontView, it shows the system shutting down, then the next log entry is 'System is up.' (6 hour lapse between those two messages, but FrontView doesn't seem to know there was a Volume Scan going on, nor does it give the results of the scan).

Does this all mean the volume scan produced nothing noteworthy?

PS: Am I right in thinking its fine to load 2x3TB drives alongside 2*2TB drives? Im using RAIDX and its a while since I pored over all the docs

Thanks