Linux Plumbers Conf 2014

One Line Summary

Abstract

SMR (shingled media recording) requires the OS to read in the list of zones to figure out the zone sizes and the status of the write pointer.
The idea here is that the OS reads the entire list to be able to make correct decisions about where the data should be written to or how I/O should be formatted.

For linux this means that initially we would need to keep the lists of zones at several layers:

- at the libata layer, as the zbc specification requires the SATL to return specific sense codes.
- at the SCSI layer, we might need to keep the write pointer up-to-date
- at the device-mapper layer, as the zone information determines the device-mapper table layout

For efficiency it would be good to keep the zone layout only once within the kernel, but the current layering forbids us to import this layer from other layers.

In this talk I will be presenting the problems during SMR integrations and discuss ways on how to overcome the layering problem.

Tags

scsi, SMR, layering

Speakers

• James Borden

  Western Digital
  • Website: http://www.wdc.com/

  Biography

  Director of Data Center Ecosystem Engagement focusing on the open-source community.

  Sessions

  • * SMR integration and how to overcome layering issues
    • Title: SMR integration and how to overcome layering issues
    • Microconference: File and Storage Systems
    • Time: 4:45pm
    • One Line Summary:

      This talk will focus on SMR integration with the linux SCSI stack and how layering issues can be overcome

    • Speakers: Hannes Reinecke, James Borden

• Hannes Reinecke

  SUSE Labs
  • Website: http://www.suse.com/

  Biography

  Studied Physics with main focus image processing in Heidelberg from 1990 until 1997, followed by a PhD in Edinburgh ’s Heriot-Watt University in 2000. Worked as sysadmin during the studies, mainly in the Mathematical Institute in Heidelberg. Now working at SUSE Labs with focus on storage and mainframe. Principal contact point for storage related issues on SLES.

  Linux addict since the earliest days (0.95); various patches to get Linux up and running. Main points of interest are storage, (i)SCSI, FC/FCoE, and multipathing. And S/390, naturally.

  I’m active on the Linux SCSI mailing list, reviewing patches and dusting out murky corners in the SCSI stack. Plus occasionally maintaining the aic79xx driver.

  Played around with kvm/qemu; I’ve implemented the megasas HBA emulation for qemu.

  Sessions

  • * First glimpse at shingled drives
    • Title: First glimpse at shingled drives
    • Microconference: Refereed Talks
    • Room: Room 14
    • Time: 3:30pm
    • One Line Summary:

      Anyone interested in modern storage technologies and trends.

    • Speakers: Hannes Reinecke
  • * SMR integration and how to overcome layering issues
    • Title: SMR integration and how to overcome layering issues
    • Microconference: File and Storage Systems
    • Time: 4:45pm
    • One Line Summary:

      This talk will focus on SMR integration with the linux SCSI stack and how layering issues can be overcome

    • Speakers: Hannes Reinecke, James Borden