IBM x3650 M1 SATA support up to 2 Tb

Yes, I have encountered this with low-end cards and buggy drivers. However, no, not on an up-to-date Adaptec rebranded card. Wow is all I can say. One thing to consider, maybe it is more a bug with the drive than the RAID controller.

I don't have a good answer, but since you seem to have exhausted most of your options other than replacing the card, (and replacing the drives did the trick) here's a few ideas you can consider for your troubleshooting:

• The WD drives were RE (RAID Edition) drives, right? The time limited error recovery is important, so if you don't have that and the drive is attempting to recover the sector, you are going to get a looooong pause from that drive. If the RAID controller is being patient and not dropping the drive you'll have a big problem on your hands.

• Check the SMART data on the drives you removed and see if there is anything interesting.

Another comment about the importance of time limited error recovery (TLER) feature, from NAS / RAID vendor support:

As I mention before, we always suggest customers to use enterprise level drives if they use the drives in RAID settings. Enterprise level drives have more consistent responding time so that the RAID will be safer.

1. I'm pretty sure there are BIOS checks on the drives, there are on other, older IBM disk arrays

2 They don't supply 2TB disks for it yet, but they likely will do and it will almost certainly support them

3 Yes, you can put in as many or as few disks, though obviously less than 5-6 it doesn't make much sense to be using it

4 The DS3400 is the identical array with a fibre channel interface, it's benchmarked using SPC-1 and SPC-2 here, the performance will be very similar

5 The server's SAS card sees the RAID controller in the DS3200 rather than the raw disks. The presentation is controlled via the IBM Storage Manager client software which connects over TCP/IP. You can build multiple RAID arrays on the DS3200, which would each appear as single disks to the server.

6 The full configuration guide is available as an IBM Redbook and includes multiple screenshots

7 The DS3200 internal controller handles the RAID

The IBM DS3000 series arrays are pretty good at what they do, they're also pretty dumb compared to most other arrays out there, but they are cheap. It's based on an LSI model, Dell sell an essentially identical MD3000 disk array.

Hope that all helps