SPC-5 and SBC-3 documents posted in support of ZBC

Ralph Weber Ralph.Weber at wdc.com
Wed Jan 8 18:09:05 PST 2014


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1401089_f.htm">HTML-formatted message</a>

Calvin,
Regrettably, I must disagree. For almost 20 years, SCSI has touted the fact
that the Initiator need not know details of how an SBC disk is constructed in
order to make effective use of that disk. In the traditional SCSI view, a SMR
disk is supposed to be exactly like a CMR disk. That has been a T10 goal for
as long as I have been a T10 member.
Since I fervently hope that the disk industry can someday return to this
highly successful equilibrium, I very much want there to be a
classic-SBC-only identification structure that some SMR disks can claim to
support.
All the best,
.Ralph
________________________________
From: owner-t10 at t10.org [owner-t10 at t10.org] on behalf of Calvin Chen
[cachen at microsoft.com]
Sent: Wednesday, January 08, 2014 12:30 PM
To: Gerry Houlder; T10 Reflector
Subject: RE: SPC-5 and SBC-3 documents posted in support of ZBC
Gerry and Ralph,
Thanks for your prompt response. From the host OS point of view, I do believe
an identification for autonomous SMR drive is needed. All currently released
host OS should treat autonomous SMR drives as CMR drives. Some future OS
development may utilize the identification information to enhance the IO
process and interaction with autonomous SMR drive. We could have some further
discussion in the coming T10 CAP meeting.
Best regards,
Calvin
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Gerry Houlder
Sent: Wednesday, January 8, 2014 8:28 AM
To: T10 Reflector
Subject: Re: SPC-5 and SBC-3 documents posted in support of ZBC
I expect T10 discussion will bring up concerns (that i have heard from at
least one systems company) about whether the proposed INQUIRY field should
allow recognition of "SBC device" (the zero case), autonomous SMR, host
assisted SMR, and ZBC device. The justification i have heard for wanting such
recognition is that they may use the information to determine which tier to
assign the drive to. For example, SBC device = tier 1, autonomous = tier 2,
host assisted = tier 2 or 3 (depending on system requirements), ZBC = tier 3.
Most folks don't see the need for all of these cases, but I'd like to listen
to the discussion on this. Some systems use the RPM indicator in the block
device characteristics VPD page to make this choice today, so this new field
would add more detail to the tier assignment choice.
On Wed, Jan 8, 2014 at 9:51 AM, Ralph Weber
<Ralph.Weber at wdc.com> wrote:
Calvin,
Here is what I think the answer to your question(s) looks like.
Device type
HAS_ZBC
Autonomous (aka Transparent) SMR
SBC
0
Host Assisted SMR
SBC
1
Restricted SMR
ZBC
???
Of course, there is a high probability that I am wrong.
All the best,
.Ralph
From: owner-t10 at t10.org<mailto:owner-t10 at t10.org>
[mailto:owner-t10 at t10.org<mailto:owner-t10 at t10.org>] On Behalf Of Gerry
Houlder
Sent: Wednesday, January 08, 2014 8:52 AM
To: Calvin Chen
Cc: t10 at t10.org<mailto:t10 at t10.org>
Subject: Re: SPC-5 and SBC-3 documents posted in support of ZBC
Current plan is autonomous drives and host assisted SMR drives will have
direct access device type while restricted SMR will have the new ZBC device
type. A field in the block device characteristics VPD page will allow
differentiation of host assisted versus restricted SMR types.
On Tue, Jan 7, 2014 at 4:30 PM, Calvin Chen
<cachen at microsoft.com> wrote:
Hi Ralph,
I have couple questions regarding the proposed SMR device identification
spec.
1.	 Will autonomous SMR, host assisted SMR and restricted SMR target
device share using the same Peripheral device type 14h = ZBC – Zoned block
device?
2.	 If a storage target device has the HAS_ZBC bit set to 0 and
Peripheral device type 14h = ZBC, does it mean the storage target device is a
restricted SMR drive?
Thanks
Calvin
From: owner-t10 at t10.org<mailto:owner-t10 at t10.org>
[mailto:owner-t10 at t10.org<mailto:owner-t10 at t10.org>] On Behalf Of Ralph Weber
Sent: Monday, January 6, 2014 6:34 PM
To: t10 at t10.org<mailto:t10 at t10.org>
Subject: SPC-5 and SBC-3 documents posted in support of ZBC
As requested by today's ZBC call, two documents are being posted for January
CAP consideration.
SPC-5: Assign device type code to ZBC
http://www.t10.org/cgi-bin/ac.pl?t=d&f=14-017r0.pdf
SBC-4: Update Block Device Characteristics VPD page for ZBC
http://www.t10.org/cgi-bin/ac.pl?t=d&f=14-018r0.pdf
See you in Irvine,
.Ralph



More information about the T10 mailing list