I am not 100% sure that 16K blocksize is the best size, for instance :
Using FreebSD 5.1 - I got the best read and write performance using a
blocksize of 32K with 4K fragments - [ reading and writing 8K blocks,
ufs1 and ufs2 fs ].
I dont have the results in front of me, but I think I tried fs
blocksizes from 4K upwards....
I am also not convinced that using 16K in Pg will be better than 8K (you
would expect sequential performance to improve, but maybe at the expense
of random ....)
regards
Mark