From owner-freebsd-hackers@FreeBSD.ORG  Thu Aug 18 17:50:06 2011
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Date: Thu, 18 Aug 2011 10:50:05 -0700
From: Yuri <yuri@rawbw.com>
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Subject: ZFS installs on HD with 4k physical blocks without any warning as
 on 512 block size device
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Some latest hard drives have logical sectors of 512 byte when they 
actually have 4k physical sectors. Here is the document describing what 
to do in such case: 
http://ivoras.net/blog/tree/2011-01-01.freebsd-on-4k-sector-drives.html .
For UFS: newfs -U -f 4096 /dev/da0
For ZFS: gnop create -S 4096 /dev/da0 && zpool create data /dev/da0.nop

I am sure most people just install such hard drive without doing this 
and potentially get suboptimal performance since they aren't aware about 
this.
Shouldn't UFS and ZFS drivers be able to either read the right sector 
size from the underlying device or at least issue a warning?

Yuri