Drives larger than 2.2 TB may appear incorrectly when attached to an eSATA port


An eSATA drive larger than 2.2TB may appear to be smaller than it's actual size when plugged in to an eSATA port. The disk may appear as the expected size if the drive is previously formatted using a different eSATA controller, USB, or 1394.  In this scenario some read or write attempts may fail.


This can happen if the controller driver underreports the total number of sectors on the disk. Drives with more than 32-bits worth of sectors are reported using 32-bits, causing an artificially low disk size to be computed. The SATA specification allows for up to 48-bits worth of sectors.  Windows uses READ CAPACITY (10) and READ CAPACITY (16) to identify the number of sectors on the disk up to 64-bits worth, as described at:

Some SATA controller drivers return 32-bit sector information to READ CAPACITY (10) when there are more than 32-bits worth of sectors on the drive. These drivers should return 0xffffffff in this scenario and return the correct number of sectors to READ CAPACITY (16).


Customers experiencing this problem should contact their SATA controller vendor for updated drivers.