Several ZBC proposals

Gerry Houlder gerry.houlder at seagate.com
Mon Jul 7 09:03:10 PDT 2014


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Your proposal 14-184 adds a "disallow unaligned writes" capability but
restricts it to one type of device and one type of zone.
If a device desires to enforce this behavior, it would want to enforce it
over all zone types within that device, not just conventional zones. it
should be written in a way that the alignment is enforced on all zone types
within the device.
Also, this behavior should be permitted for all device types so either host
managed zoned block devices or host aware zoned block devices are allowed
to implement this feature and and bit in the VPD page that indicates the
behavior.
This proposal may also open the door for folks that would like to reject
unaligned writes on existing direct access devices. Those folks would like
to have the bit located in VPD page B1h (block device characteristics) page
so that devices that are not zoned block devices may use this capability.
In this eventuality, the entire proposal would move to SBC-4 and not be
restricted to zoned block devices.
On Mon, Jul 7, 2014 at 10:36 AM, Joe Breher <Joe.Breher at hgst.com> wrote:
>  One of my collaborators has caught that I have mischaracterized one of
> the below-listed proposals - in it's very title. I will include a change to
> this in r1. Please see below for correction.
>
>   Joe Breher
>  (478) 2-Breher
>  (478) 227-3437
>
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>  On Jul 7, 2014, at 2:37 AM, Joe Breher wrote:
>
>  * From the T10 Reflector (t10 at t10.org), posted by:
> * Joe Breher <Joe.Breher at hgst.com>
> *
> I have tendered several proposals for consideration under ZBC. I'd love to
> be able to present these in today's call.
>
> 14-181R0 2014/07/07 ZBC Discussion: Active zones and host managed pinning
> - a view of the transitions between zone conditions, and a means for hosts
> to control where latencies due to resource management are incurred
>
> 14-182R0 2014/07/07 ZBC: Read across sequential write required zone
> boundary
> 14-183R0 2014/07/07 ZBC: Read unwritten sequential write required zone
> - two related optional behavioral changes with indications thereof
>
> 14-184R0 2014/07/07 ZBC: Disallow unaligned writes for host aware devices
>
>
>  Should be: "ZBC: Disallow unaligned writes for host aware * managed*
> devices"
>
>  - why must we support unaligned accesses on conventional zones on host
> managed zoned block devices? Just say no.
>
> Thanks -
>
> Joe Breher
> (478) 2-Breher
> (478) 227-3437
>
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