On 5/3/2010 4:27 PM, Martin K. Petersen wrote:

We have means of obtaining alignment and physical sector size
information from both SCSI and ATA drives.  But only if the drive
firmware provides the information, of course.

How?  I don't see any such information in the output of hdparm -I for
instance.

One currently shipping drive model on the market isn't reporting the
bigger physical block size.  But there are several other 4KB sector
products out there that are working just fine.

The WD drive indeed reports a 512 byte sector size, but I also have an
SSD with a 512kb erase block size and it seems like these knobs were
intended to cover that as well, but again, the values exported by the
kernel in /sys are 0 and I don't see a way for the drive to report this
information to the kernel.