LIO

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LIO Linux SCSI Target
Logo
LIO 150513.png
Linux SCSI Target
Original author(s) Nicholas Bellinger
Developer(s) Datera, Inc.
Initial release January 14, 2011 (2011-01-14)
Stable release 4.1.0 / June 20, 2012;
7 years ago
 (2012-06-20)
Preview release 4.2.0-rc5 / June 28, 2012;
7 years ago
 (2012-06-28)
Development status Production
Written in C
Operating system Linux
Type SCSI Target engine
License GNU General Public License
Website datera.io
LIO architecture overview.
LIO iSCSI architecture diagram.
SCSI Portal Group and multipath architecture overview.
SCSI standards diagram.
QLogic Fibre Channel running at line rate in target mode with PCIe device passthrough and MSI-X polled interrupts across Linux/SCSI qla2xxx LLD request and response rings.
The IEEE Firewire driver exporting IBLOCK LUNs to a MacOS-X based IEEE-1394/FireWire client.

The LIO Linux SCSI Target has become the Linux block storage standard with kernel version 2.6.38.[1][2] It supports a rapidly growing number of fabric modules, and all existing Linux block devices as backstores.

Contents

Overview

The Linux SCSI Target core is a SCSI engine that implements the semantics of a SCSI target as described in the SCSI Architecture Model (SAM), and supports its comprehensive SPC-3/SPC-4 feature set in a fabric-agnostic way. The SCSI target core does not directly communicate with initiators and it does not directly access data on disk.

The Linux SCSI Target has obtained VMware vSphere 4 Ready certification on Buffalo [PDF] and QNAP [PDF] systems, and vSphere 5 Ready certification on Netgear [PDF] and Pure Storage [PDF] systems.

Native support in OpenStack (setup, code), starting with the Grizzly release, makes the Linux SCSI Target also an attractive storage option for cloud deployments.

The Linux SCSI Target core (target_core.ko, see Linux kernel driver database) was released with the Linux kernel 2.6.38 on January 14, 2011 (2011-01-14).[3]

Setup

targetcli provides a comprehensive, powerful and easy CLI tool to configure and manage LIO SCSI Targets. targetcli was developed by Datera, Inc..

Fabric modules

Fabric modules implement the "frontend" of the SCSI target. They "speak" specific protocols that transport SCSI commands. The Fabric Hardware Abstraction Layer (F-HAL) allows all protocol-specific processing to be encapsulated in fabric modules. The following fabric modules are available:

Backstores

Backstores implement the "backend" of the SCSI target. They implement the methods of accessing data on disk. A backstore subsystem plugin is a physical storage object that provides the block device underlying a SCSI Endpoint.

Backstore objects can be added via the Storage Hardware Abstraction Layer (S-HAL) that brings storage hardware into the SCSI Target engine as raw block devices, on which the Linux stack just works (including complex functionality such as software RAID, LVM, snapshots, virtualization, etc.).

The SCSI Target supports the SCSI-3 standard for all backstore devices (block devices and/or VFS):

The SCSI functionality is implemented directly in the target engine in a fabric-agnostic way, including a number of high-end features, such as Persistent Reservations (PRs) and Asymmetric Logical Unit Assignment (ALUA), following the SPC-4 standard.

The backstore devices (FILEIO, IBLOCK, pSCSI, RAMDISK, etc.) report the underlying HW limitiations for things like TCQ depth, MaxSectors, TaskAbortedStatus, UA Interlocking, etc. All of these values are available as attributes in the targetcli device context.

Specifications

The following specifications are available as T10 Working Drafts:

Glossary

Inclusion in Linux distributions

The LIO SCSI Target and targetcli are included in most Linux distributions per default. Here is an overview over the most popular distributions:

Distribution Version[Linux 1] Release Archive Install Source git[Linux 2] Documentation
CentOS 6.2 2011-12-20 CentOS mirror su -c 'yum install fcoe-target-utils' targetcli-fb.git Tech Notes
Debian 7.0 ("wheezy") TBA Debian pool su -c 'apt-get install targetcli' targetcli
Fedora 16, 17/18 2011-11-08 Fedora Rawhide su -c 'yum install targetcli' targetcli-fb.git Target Wiki
openSUSE 12.1 2011-11-08 Requires manual installation from targetcli.
RHEL 6.2 2011-11-16 Fedora Rawhide su -c 'yum install fcoe-target-utils' targetcli-fb.git Tech Notes
Scientific Linux 6.2 2012-02-16 SL Mirror su -c 'yum install fcoe-target-utils' targetcli-fb.git Tech Notes
SLES SP2 2012-02-15 Requires manual installation from targetcli.
Ubuntu PrecisePangolin v12 2012-04-26 Ubuntu universe su -c 'apt-get install targetcli' targetcli
  1. The distribution release where LIO was included first.
  2. Technical support, and qualified backports to other kernels and distributions are available from Datera.

Timeline

The LIO SCSI Target and fabric modules have gone upstream into the Linux kernel as follows:

Wikipedia

Contact

Please direct all technical discussion on targetcli to the target-devel mailing list (post, subscribe, list info, gmane archive).

If you need assistance, or if you have an SLA with Datera, Inc., please contact the company at:

Please see Support for more information.

See also

Notes

  1. Thorsten Leemhuis (2011-03-02). "Kernel Log: Coming in 2.6.38 (Part 4) - Storage". Heise Online. 
  2. Jonathan Corbet (2010-12-22). "Shooting at SCSI targets". lnw.net. 
  3. Linus Torvalds (2011-03-14). "Linux 2.6.38". lkml.org. 
  4. Mark J. Sullivan (January 2010). Intel® Xeon® Processor C5500/C3500 Series Non-Transparent Bridge. 323328-001. Santa Clara: Intel. 
  5. Linus Torvalds (2011-03-14). "Linux 2.6.38". lkml.org. 
  6. Linus Torvalds (2011-01-14). "Target merge". lkml.org. 
  7. Linus Torvalds (2011-05-18). "Linux 2.6.39". lkml.org. 
  8. Linus Torvalds (2011-07-21). "Linux 3.0". lkml.org. 
  9. Linus Torvalds (2011-10-24). "Linux 3.1". lkml.org. 
  10. Linus Torvalds (2011-07-27). "iSCSI merge". lkml.org. 
  11. Linus Torvalds (2012-03-18). "Linux 3.3 release". lkml.org. 
  12. Linus Torvalds (2012-01-18). "InfiniBand/SRP merge". lkml.org. 
  13. Linus Torvalds (2012-07-21). "Linux 3.5 released". marc.info. 
  14. Linus Torvalds (2012-05-31). "scsi-misc". lkml.org. 
  15. Linus Torvalds (2012-05-22). "usb-target-merge". lkml.org. 
  16. Linus Torvalds (2012-05-23). "sbp-target-merge". lkml.org. 
  17. Linus Torvalds (2012-10-01). "Linux 3.6". lkml.org. 
  18. Linus Torvalds (2012-08-13). "tcm_vhost: Initial merge for vhost level target fabric driver". lkml.org. 
  19. Linus Torvalds (2013-04-28). "Linux 3.9 released". lkml.org. 
  20. Linus Torvalds (2013-06-30). "Linux 3.10". marc.org. 

External links

Timeline of the LinuxIO
Release Details 2011 2012 2013 2014 2015
123456789101112 123456789101112 123456789101112 123456789101112 123456789101112
4.x Version 4.0 4.1
Feature LIO Core Loop back FCoE iSCSI Perf SRP
CM WQ FC
USB
1394
vHost Perf Misc 16 GFC iSER Misc VAAI Misc DIF Core
NPIV
DIF iSER DIF FC vhost TCMU Xen Misc Misc virtio 1.0 Misc NVMe OF
Linux 2.6.38 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 3.22
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