FreeBSD 8.x and 4K sector disks
FreeBSD 8.x and 4K sector drives
FreeBSD 8.x (and older) use sysinstall as the install mechanism and fdisk for disk slicing/partitioning. Unfortunately, these utilities perform calculations based on a 512B sector size. This causes problems with drives of a sector size greater than this. 4K sector size drives are the most popular at this point.
I cannot explain the problem and solutions any better than Ivan Voras (FreeBSD source contributor since 2008), so I link to his blog here.
There are good tidbits of information in the comments such as sysinstall not understanding gpart, etc. It would be a good idea to read through the comments as well.
Categories: FreeBSD
FreeBSD 9 does not address this by default either, but it is far easier to mitigate the issue during install in 9.x vs. 8.0. Here is a blog post that explains dealing with the issue in FreeBSD 9.x and newer: https://www.ateamsystems.com/blog/FreeBSD-Partition-Alignment-RAID-SSD-4k-Drive?goback=%2Egmp_47628%2Egde_47628_member_131408913