I recently purchased a Dell Poweredge 2950 at an auction for a very low price, couldn't pass it up. It didn't come with any hard drives so I ordered 5 SATA caddy trays and I am curious what the maximum size the hard disks could be. I plan on doing RAID 6 so I have plenty of redundancy and I would like to have at least 1TB drives installed. Will the 2950 support 5-6 1TB drives or maybe even 2TB drives? I'm not concerned whether or not dell "supports it". I have already tested a WD Green 500GB SATA drive I had lying around and it worked fine in the SAS bay. Also, will the caddys I ordered still have lights that tell me whether or not a drive is dead or is that just an SAS thing?
2TB drives (2.5" and 3.5") will work on the PERC 5, 6, and H700.
3TB drives are only supported on the PERC H700; support was added via firmware update, so if you buy one, make sure to update the controller firmware for 3TB support. 3TB support is controller-specific, not system specific, so an H700 in a 2950 would take 3TB drives and a PERC 6 in an R710 would not.
In order for Windows OS's to use a >2TB, the "disk" must be converted to GPT. Windows OS's CAN boot to GPT IF using 64-bit Vista/2008 (or later) installed on a UEFI-enabled system (which the R710 is but the 2950 is not).
As far as the lights, I believe the lights on the caddy should work as you would expect, but it's been a while since I had one to play with.
Support Documentation: http://en.community.dell.com/support-forums/servers/f/906/t/19309039.aspx