[dm-devel] SMR 512e drive firmware advertising misleading limits? [was: Re: [RFC PATCH 1/1] dm: add dust target]

[Mike Snitzer]

On Tue, Jan 08 2019 at  8:03pm -0500,
Damien Le Moal <Damien.LeMoal at wdc.com> wrote:
 
> You may want to check against the physical_block_size, and not the logical. SMR
> disks that are 512 e (512B logical and 4K physical) can handle reads in 512B
> units but writes have to be 4K. These are exceptions though and kind of breaking
> all LBA definitions known to men... This check on the physical_block_size can be
> limited to setups where the underlying disk is SMR.

Damien, this sounds like a serious issue with SMR firmware.  If the
512e SMR drive cannot handle 512b writes then it has no business
advertising 512B logical.  It should be advertising 4K logical.

What am I missing?

Mike