Open-iSCSI project: Open-iSCSI – RFC3720 architecture and implementation

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News

Linux-iSCSI(sfnet) and Open-iSCSI projects merged!(April 11, 2005)

After a lot of discussions between the teams the conclusion was reached that taking the open-iscsi source as the basis for the "next generation" of linux-iscsi is the best course of action. See the related announcement.

First bits released!(February 18, 2005)

We are proud to announce first development release. First version is not very usable yet but you'll get the idea.

Official Web site(January 1, 2005)

We've opened official web site and registered new open-iscsi group with google groups.

Introduction

What is Open-iSCSI?

Open-iSCSI project is a high performance, transport independent, multi-platform implementation of RFC3720. Goals and features:

Data Path & Performance

The data path code lives in the kernel and concerns itself only with moving data. The best performance on any given platform is the major requirement for Open-iSCSI project.
Today's numbers are:

single iSCSI session:

450MB/s Read and 450 MB/s Write for 64KB block
510 MB/s Read and 550 MB/s Write for 256KB block
65,000 IOPS - 1K, 58,000 IOPS - 2K, 50,000 IOPS with 4KB Read

two iSCSI sessions:

550 MB/s Read and 810 MB/s Write for 256KB block
75,000 IOPS for 1K block

(single connection, 10GbE network, 2.4Ghz dual Opteron, UNH or IET targets).

Minimal footprint in the kernel

It is our strong opinion that existing Initiators bloat the kernel with ever-growing control plane code, including but not limited to: iSCSI discovery, Login (Authentication and Operational phases), session and connection management, connection-level error processing, iSCSI Text, Nop-Out/In handling, iSNS, SLP, Radius...
One of our project's initial and primary requirements: the entire control plane resides in the user space.

User/Kernel Interface

User/Kernel interface for Open-iSCSI means - the interface between Control and Data planes. This asynchronous interface is implemented using Netlink Sockets.

Documentation

README
Open-iSCSI modules Startup, Login, Read/Write Recovery
Multi-Transport Connection State Diagram

Developer's Corner

Build requirements:

Linux kernel >= 2.6.16

Git repository on kernel.org

To get the current development kernel and userspace code used for open-iscsi.org releases the open-iscsi git tree should be used.

On-line Viewer:

http://git.kernel.org/?p=linux/kernel/git/mnc/open-iscsi.git;a=summary

To download the tree run:
git clone git://git.kernel.org/pub/scm/linux/kernel/git/mnc/open-iscsi.git

If your distro does not have a git package, it can be downloaded from kernel.org

For the latest kernel code against the current upstream development kernel download the iscsi git tree and checkout the iscsi branch:

git clone git://git.kernel.org/pub/scm/linux/kernel/git/mnc/linux-2.6-iscsi.git
git checkout -b my_iscsi_branch origin/iscsi
With older git versions checkout the branch with:
git checkout iscsi

This git repository should only be used be kernel developers wanting to send a patch upstream (kernel.org/Linus/mainline/upstream kernel) or users that want to help test the latest code against the current development kernel.

On-line Viewer:

http://kernel.org/git/?p=linux/kernel/git/mnc/linux-2.6-iscsi.git;a=summary