3tb esternal USB hard drives under 4.2.17

sphardy wrote:

No where in this thread do I see verification that the 3TB drives have been partitioned using GPT as questioned by @mdgm. It is important to ensure the correct partition type is used as the ReadyNAS will not re-partition an already partitioned USB drive, only reformat it. (Partitioning of new completely blank drives is of course supported) The 2 major partition types are MBR and GPT. MBR is limited disks to 2TB capacities - which is why Netgear added GPT support - and the symptoms described are typical of MBR partitioned drives This does not rule out USB controller limitations, but it should at least be investigated before making any conclusions. How to verify the partition format will depend on your hosts' OS, but is typically reported by the OS disk utilities

Ah yes, I knew I was forgetting to mention something important. Under windows the only controller that could see the whole disk also showed that the MBR was there and provided the option of creating a 2tb partition and leave the remaining 0.75TB unused. However, on a Windows 7 box I was able to click on the left side of "disk manager" and one of the options was convert disk to GPT. Prior to that point while the readynas would report 27xx GB of disk space when formatted to ext3 it would provide a 2048GB partition. Once the conversion from MBR to GPT took place then when formatted I got a 2.7TB disk.

I went back to the old controllers as a test and found the same issues as before so looks like a mixture of GPT vs MBR and controller limitations.