How to get UFS filesystem block size in FreeBSD using "dumpfs" utilityCode:
# dumpfs /var/ | grep "bsize"
bsize 16384 shift 14 mask 0xffffc000
maxbsize 16384 maxbpg 2048 maxcontig 8 contigsumsize 8
sbsize 2048 cgsize 16384 csaddr 3000 cssize 2048
Default UFS filesystem block size in FreeBSD is 16 K ( and from my reading, this is a decent value, but care needs to be taken when deploying Postgresql on FreeBSD - both UFS block size and Postgresql blocks should be at the same size).