_ It occurs to me that WD Align must be able to detect when the 7-8 jumper is installed. If it were to merely base its judgment on the starting sector number, then it would incorrectly identify those single partition XP installations which have been correctly aligned by means of the AF jumper. _
_ AIUI, the function of the jumper is to add a +1 sector offset to each LBA so that when the OS accesses sector 63, the drive transparently maps it to LBA 64, thereby aligning the partition. _
_ The ATA standard provides several words in the Identify Device information block that enable the drive to report the sizes of its logical and physical sectors, and whether a sector offset is active. For example, word 209 reports the “alignment of logical blocks within a physical block”, and word 106 indicates that the ratio of Physical sector size to Logical sector size. _
Working Draft AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS):
http://www.t13.org/documents/UploadedDocuments/docs2008/D1699r6a-ATA8-ACS.pdf
_ The following thread has an example of the Advanced Format words for a WD20EARS: _
I never put a jumper on pins 7-8 as I do not want a single partition. After purchasing the drive, I learnt that it is an AF drive. So, I read the info available on WD website. Since it is clearly stated that the jumper option ONLY ALLOWS ONE SINGLE PARTITION (that too on OLDER drives only), I scratched that option long time ago. Only option available now is to align the partitions through software.
