Hi Robert, On Thu, 2012-11-15 at 20:01 +0000, Elliott, Robert (Server Storage) wrote: > WRITE SAME always has a payload, regardless of the UNMAP bit value. > > For WRITE SAME with UNMAP=0, it's extremely important; that's how what > to write is specified. > > For WRITE SAME with UNMAP=1, the device server is required to check > that the payload matches the data that is returned for unmapped LBAs. > lf LBPRZ=1 (read zeros for unmapped LBAs), that means checking that > the payload has all zeros. In sbc3r33, this rule is tucked away in > model section 4.7.3.4.3, not the command section 5.41. > > I would like to change that rule (it's a nuisance and a performance > burden), but that's the current rule going into SBC-3 letter ballot. > > Changing WRITE SAME with UNMAP=1 to ignore the payload would provide > essentially the same functionality as changing the UNMAP command to be > mandatory, not just a hint; both approaches have been discussed. > Thanks for the heads up here.. I'm making the slight change to the -v2 patch series that just went out to always check the max_write_same_len value for both WRITE_SAME w/ UNMAP=[1,0] cases. Thank you, --nab -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
