mirror of
https://github.com/SCST-project/scst.git
synced 2026-07-31 04:23:09 +00:00
Vladislav Bolkhovitin
f42a81e94a
git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@1490 d57e44dd-8a1f-0410-8b47-8ef2f437770f
150 lines
7.5 KiB
HTML
150 lines
7.5 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta name="Keywords" content="Generic SCSI Target Subsystem for Linux, iSCSI, iSCSI target, iSCSI-SCST">
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="author" content="Daniel Fernandes">
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<meta name="Robots" content="index,follow">
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<link rel="stylesheet" href="images/Orange.css" type="text/css">
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<title>iSCSI Target Driver</title>
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</head>
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<body>
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<!-- wrap starts here -->
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<div id="wrap">
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<div id="header">
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<div class="logoimg"></div><h1 id="logo"><span class="orange"></span></h1>
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<h2 id=slogan>Generic SCSI Target Subsystem for Linux</h2>
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</div>
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<div id="menu">
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<ul>
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<li><a href="index.html">Home</a></li>
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<li><a href="http://www.sourceforge.net/projects/scst">Main</a></li>
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<li><a href="http://sourceforge.net/news/?group_id=110471">News</a></li>
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<li id="current"><a href="targets.html">Drivers</a></li>
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<li><a href="downloads.html">Downloads</a></li>
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<li><a href="contributing.html">Contributing</a></li>
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<li><a href="comparison.html">Comparison</a></li>
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<li><a href="users.html">Users</a></li>
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<li><a href="solutions.html">Solutions</a></li>
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</ul>
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<!-- content-wrap starts here -->
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<div id="content-wrap">
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<div id="sidebar">
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<h1>Target Drivers</h1>
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<ul class="sidemenu">
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<li><a href="target_iscsi.html">iSCSI-SCST</a></li>
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<li><a href="target_qla2x00t.html">QLogic FC QLA2X00T</a></li>
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<li><a href="target_qla_isp.html">QLogic FC ISP</a></li>
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<li><a href="target_srp.html">SCSI RDMA Protocol (SRP)</a></li>
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<li><a href="target_mvsas.html">Marvell SAS adapters</a></li>
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<li><a href="target_emulex.html">Emulex lpfc FC/FCoE adapters</a></li>
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<li><a href="target_lsi.html">LSI/MPT adapters</a></li>
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<li><a href="target_fcoe.html">Open-FCoE Target</a></li>
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<li><a href="target_local.html">Local Target Driver</a></li>
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<li><a href="target_old.html">Old Unsupported</a></li>
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</ul>
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<h1>User utilities</h1>
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<ul class="sidemenu">
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<li><a href="scst_admin.html">SCST Admin Utility</a></li>
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<li><a href="handler_fileio_tgt.html">FILEIO_TGT handler</a></li>
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</ul>
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</div>
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<div id="main">
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<h1>ISCSI target driver iSCSI-SCST</h1>
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<p>ISCSI-SCST is an iSCSI target driver for SCST. It is a deeply reworked fork of
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<a href="http://iscsitarget.sourceforge.net/">IET</a> with a lot of fixes and improvements. Reasons of the fork were:</p>
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<ul>
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<li><span>To be able to use full power of SCST core.</span></li>
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<li><span>To fix all the problems, corner cases issues and iSCSI standard violations which IET has.</span></li>
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</ul>
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<p>IET in many corner cases has a lot of problems, like ignoring errors processing, as it is for memory allocations,
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crashing itself with BUG() macro, as it is for malformed packets from initiators, possible data
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corruptions, because of, for instance, unsafe task management or sessions reinstatement implementations, etc.
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There was no way to fix all them without a fork, because it needed a deep code redesign to fix all internal architecture
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and implementation issues which IET has. As the result of this effort nearly all (>90% overall and almost 100%
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of the fast path core) of the IET kernel code and 20-25% of the user space code were rewritten.</p>
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<p>You can find comparison of iSCSI-SCST with IET and other iSCSI targets on the <a href="comparison.html">Comparison</a> page.
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Some highlights:
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</p>
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<ul>
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<li><span>Improved performance. In some cases improvement >100%.</span></li>
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<li><span>Pass-through mode with one to many relationship, when multiple initiators can connect to
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exported local SCSI devices. For instance, in this mode you can safely export your parallel
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SCSI tape or tape library, or VTL on your iSCSI net and multiple initiators can share it without risk of
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data loss because of the shared usage.</span></li>
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<li><span>Automatic PnP-like reconfiguration, when initiators instantly see any configuration changes on the
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target, like addition of new LUNs or a LUN resize. No restart or anything like that is needed.</span></li>
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<li><span>Safe implementation of many management and errors recovery facilities as well as better handling of various
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corner cases, which means better errors recovery stability without putting user data at risk.</span></li>
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<li><span>Advanced devices visibility management, when different initiators can see different set of
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devices from the same target.</span></li>
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<li><span>O_DIRECT, i.e. "BLOCKIO on files", mode, which has all advantages
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of BLOCKIO, but also supports files on file systems. Sometimes, in the appropriate cases,
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this mode can make performance difference in 100% or even more.</span></li>
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<li><span>4KB blocks eliminate abysmal write performance issues caused by misaligned partitions.
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</span></li>
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<li><span>Virtual CD/DVD-ROMs.</span></li>
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<li><span>Ability to create target devices emulators in the user space.</span></li>
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<li><span>Ability to create multi-transport SCSI targets, which can export (possibly, the same)
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devices over multiple transports.</span></li>
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</ul>
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<p>If you are an IET user before installation carefully read README files of both iSCSI-SCST and
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the SCST core. Especially pay attention that now the LUN information for iSCSI-SCST is configured not using
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iscsi-scstd.conf file in /etc, but using corresponding SCST facilities. This is because now responsibilities
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are divided (as it logically should be) between the target driver (iSCSI-SCST) and the SCSI target core (SCST),
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where target driver is responsible for handling targets with their parameters, and SCST core is responsible for handling
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backstorage.</p>
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<p>The latest stable version is 1.0.1.1. Requires Linux kernel version 2.6.16.x or higher and SCST version 1.0.1.1 or higher.
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Tested mostly on i386 and x86_64, but should work on any other supported by Linux platform.</p>
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<p>You can find the latest development version of this driver in the SCST SVN. See the download page how to setup
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access to it.</p>
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<p class="post-footer align-right">
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<a href="iscsi-scst-howto.txt" class="readmore">HOWTO</a>
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<a href="SCST_Gentoo_HOWTO.txt" class="readmore">Gentoo HOWTO</a>
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<a href="downloads.html" class="readmore">Download</a>
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<a href="http://scst.svn.sourceforge.net/" class="readmore">SCST SVN Repository</a>
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</p>
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</div>
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<p>© Copyright 2004-2009<b><font class="names"> Vladislav Bolkhovitin & others.</font></b>
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Design by: <b><font class="names">Daniel Fernandes</font></b> </p>
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