[Stgt-devel] User-space iSCSI target driver

FUJITA Tomonori fujita.tomonori
Mon Sep 4 03:41:28 CEST 2006

From: FUJITA Tomonori <fujita.tomonori at lab.ntt.co.jp>
Subject: [Stgt-devel] User-space iSCSI target driver
Date: Sun, 03 Sep 2006 20:32:59 +0900

> Seems that the user-space iSCSI target driver is ready for people who
> are interested in iSCSI target development. It provides the very basic
> features with reasonable performance (should be comparable with
> IET). As long as the initiators and network work well, the target
> driver should be ok.

Here's a quick explanation of the user-space driver concept (it is not
mentioned in the OLS paper).

The majority of tgt drivers live in kernel space and send SCSI
commands to the user-space daemon through shared memory between kernel
and user space (we used netlink for this in the past) via in-kernel
tgt part. The user-space daemon provides SCSI-target common features:
SCSI protocol processing, logical unit and target device management,

In the user-space driver concept, tgt drivers live in user space and
directly send SCSI commands to the user-space daemon via user-space
tgt APIs (tgt and user-space drivers are complied to a single
binary). The drivers still enjoy the common features though there is
no kernel involvement.

The user-space iSCSI target driver is the first example. I guess that
SRP and SBP target driver could live in user space too.

> svn checkout svn://svn.berlios.de/stgt/trunk

The README.iscsi file in the doc directory should be useful if you try
the iSCSI target driver.

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