[T10] [T13] webex: Online Logical DePop

Joe Breher Joe.Breher at hgst.com
Wed Mar 30 15:33:22 PDT 2016


Hello All -

The notes I took at the meeting are now posted as both T10 and T13 docs.

File Number: f16117r0
Title: Webex notes - Joint T10/T13 - Online Logical DePop
Description: Notes from the joint T10/T13 webex on Online Logical DePop
PDF Document: http://www.t13.org/documents/UploadedDocuments//docs2016/f16117r0-Webex_notes_-_Joint_T10T13_-_Online_Logical_DePop.pdf

Your request to upload a file or files to the T10 site has been accepted.
Your PDF file will be posted at:
  http://www.t10.org/cgi-bin/ac.pl?t=d&f=16-113r0.pdf

Please feel free to respond with any amplifications or corrections.

Joe Breher
Storage Architecture Technologist
Standards Setting Organization
San Jose Research Center
Western Digital
(478) 2-Breher
(478) 227-3437


[cid:3888D38D-876F-48C4-94D6-BF5B836DAD27 at gateway.innflux.com]





On Mar 30, 2016, at 12:49 PM, Joe Breher <Joe.Breher at hgst.com<mailto:Joe.Breher at hgst.com>> wrote:

All -

Thank you for your interest in Online Logical DePop (OLDP). In regards to an agenda, I think at this point most progress can be made by identifying where we have consensus, and where viewpoints differ. Pursuant to this, I have annotated the following outline of several major chunks of functionality in the vision. I would like to capture which points of agreement there are in the following, as well as any dissenting viewpoints.

What are the primitive operations?
DEPOP
queries
TRUNCATE
AMPUTATE
REGENERATE



DEPOP
Input: Physical Element identifier
Performs depopulate operation
Removes LBA mapping resources from use
All LBAs associated with those LBA mapping resources are in new state
Unreadable (new ASCQ)
Writable (given uncommitted LBA mapping resources on other physical element)
Act of writing moves to new state
MAPPED in Resource or Thin provisioned LBP model
'not trimmed' in ACS model
'nominal' in SCSI Fully provisioned model (not supporting LBP)
What happens to the user data?
All user data in LBAs associated with the depopped physical element are lost
Host may move what it can before depop
Aided by GET LBA MAPPING
Input: physical element identifier
Output: list of LBA ranges
Note: point in time
Rebuild Assist would also be useful here
After depop will be too late
All user data associated with other physical elements dependent on command
DEPOP retains access to user data in these LBAs
DEPOP with TRUNCATE and FORMAT reformats entire device server - all user data eradicated



Queries
GET LBA STATUS
Inputs
Starting LBA
Allocation length
Outputs
List of LBA status descriptors
LBA
Block count
Provisioning status
Mapped
Deallocated
Anchored
New: Depopulated
New: Amputated
GET EXTENDED LBA STATUS
Similar to GET LBA STATUS, but adds:
Input: LBP State (similar to REPORTING OPTIONS in ZAC/ZBC  REPORT ZONES)
Can this be merged into GET LBA STATUS?
E.g. byte 14 7:0 or byte 1 7:5
GET LBA MAPPING
Inputs
Physical element identifier
Starting LBA
Allocation Length
Outputs
List of LBA Range descriptors
Physical Element status input page
Diagnostic page on SCSI, log page on ATA
List of physical element status descriptors
Normalized health value per physical element
Logical Block Provisioning log page
In SCSI, port to ATA
Available LBA Mapping Resource Count
Used LBA Mapping Resource Count
New: Underprovisioned Count



TRUNCATE
Simply 'lops off' highest-numbered LBAs
Input: LBA
READ CAPACITY data affected
Physical capacity (number of LBA mapping resources) unaffected
What happens to user data?
All user data in LBAs above specified limit will be lost
Host can move before operation
All user data below specified limit unaffected
No remapping of data<>LBA

Thanks -

Joe Breher
Storage Architecture Technologist
Standards Setting Organization
San Jose Research Center
Western Digital
(478) 2-Breher
(478) 227-3437


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