CAM Shingled Disk support patches available

[Slawa Olhovchenkov]

On Mon, Jan 18, 2016 at 05:37:04PM -0500, Kenneth D. Merry wrote:

> I have a new set of SMR patches available.  See below for the full
> explanation.
> 
> The primary change here is that I have added SMR support to the ada(4)
> driver.  I spent some time considering whether to try to make the da(4) and
> ada(4) probe infrastructure somewhat common, but in the end concluded it
> would be too involved with not enough code reduction (if any) in the end.
> 
> So, although the ideas are similar, the probe logic is separate.
> 
> Note that NCQ support for SMR commands (Report Zones, Reset Write Pointer,
> etc.) for SATA protocol shingled drives isn't active.  For both the da(4)
> and ada(4) driver this is for lack of a way to plumb the ATA Auxiliary
> register down to the drive.
> 
> In the ada(4) case, we need to add the register to struct ccb_ataio and
> add support in one or more of the underlying SATA drivers, e.g. ahci(4).
> 
> In the da(4) case, it will require an update of the T-10 SAT spec to
> provide a way to pass the Auxiliary register down via the SCSI ATA
> PASS-THROUGH command, and then a subsquent update of the SAT layer in
> various vendors' SAS controller firmware.  At that point, there may be 
> an official mapping of the SCSI ZBC commands to the ATA ZAC commands, and
> we may be able to just issue the SCSI version of the commands instead of
> composing ATA commands in the da(4) driver.  (We'll still need to keep the
> ATA passthrough version for a while at least to support controllers that
> don't have the updated translation code.)

Please, check me: currenly SMR lack of support in SCSI devices? On
[hardvare] vendor level? Currenly only SATA controllers compatible
with SMR (on command level)? (I am don't talk about FreeBSD support,
question about common state).