From 5d4789c8c02aa4fc946ac2379d537598bb5c4f4e Mon Sep 17 00:00:00 2001
From: Vladislav Bolkhovitin <vst@vlnb.net>
Date: Wed, 15 Aug 2007 09:59:46 +0000
Subject: [PATCH] ISCSI-SCST updates

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@163 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 www/scst_page.html | 102 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 100 insertions(+), 2 deletions(-)

diff --git a/www/scst_page.html b/www/scst_page.html
index 63546e8fc..7b5940469 100644
--- a/www/scst_page.html
+++ b/www/scst_page.html
@@ -201,6 +201,104 @@ enabling/disabling target mode on your target SCSI controller.<br>
 <p><a
  href="http://sourceforge.net/project/showfiles.php?group_id=110471">Download</a>
 </p>
+<hr
+ style="width: 100%; height: 2px; margin-left: 0px; margin-right: 0px;">
+<h1><small>ISCSI target driver iSCSI-SCST<br>
+</small></h1>
+<div style="text-align: justify;">
+<p>ISCSI-SCST is a forked (with all respects) version of <a
+ href="http://iscsitarget.sourceforge.net/">IET</a> with
+updates to work over SCST as well as with many improvements and
+bugfixes. The reason of fork is that the necessary changes are
+intrusive and with the current IET merge policy, where only simple
+bugfix-like patches, which doesn't touch the core code, could be
+merged, it is very unlikely that they will be merged in the main IET
+trunk.<br>
+</p>
+<p>ISCSI-SCST has the following major advantages over the mainline IET:<br>
+</p>
+<ul>
+  <li>It uses full SCST power without loosing any existing feature
+(except, maybe, "illegal" from SCSI specifications point of view MPIO).
+Namely, you can use with it:</li>
+</ul>
+<ul style="list-style-type: circle; margin-left: 40px;">
+  <li>Pass-through mode with one to many relationship, i.e. when
+multiple initiators can connect to the exported pass-through devices
+(see above). For instance, you can safely export your parallel SCSI
+tape or tape library on your iSCSI net and multiple initiators can
+share it without risk of data loss because of the shared usage.
+Existing "rawio" patch for IET supports only non-enforced 1:1
+relationship, so it is unsafe to use it in multiple initiators
+environments.<br>
+  </li>
+  <li>More advances devices visibility management, when different
+initiators can see different set of devices with different access
+permissions from the same target.</li>
+  <li>O_DIRECT, i.e. "BLOCKIO on files", mode, which has all advantages
+of BLOCKIO, but also supports files on file systems. Sometimes, in the
+appropriate cases, this mode can make performance difference in 100% or
+even more.</li>
+  <li>With 4KB blocks you can forget about abysmal write performance
+caused by misaligned partitions. All modern OS'es, including Windows
+starting from, at least, Windows 2000, work perfectly with 4KB block
+devices without any additional storage or handling overhead.</li>
+  <li>Virtual CD/DVD-ROMs without necessity for manual patching.</li>
+  <li>Ability to create target devices emulators in the user space.</li>
+  <li>Ability to create multi-transport SCSI targets, which can export
+(possibly, the same) devices over multiple transports.</li>
+</ul>
+<ul>
+  <li>It has many code improvements and cleanups, including stability
+and iSCSI RFC violations fixes. If you are an IET user and consider IET
+problemless, I'm sorry for the bad news. IET works well only on "fast"
+paths and regularly used branches, in many other less used cases IET
+has various problems, from simply ignoring error processing, as it is
+with memory allocations, to crashing itself with BUG() macro, as it is
+for malformed packets from initiators. ChangeLog file lists most
+noticeable fixes, but there were a lot of many other smaller ones.</li>
+</ul>
+<ul>
+  <li>Due to its reworked IO architecture and SCST backend iSCSI-SCST
+has better performance in many cases. In future with upcoming SCST
+improvements, like zero-copy with Linux cache FILEIO, the performance
+difference is going to be even bigger. Currently in tests from a single
+initiator over a single connection on 1GbE hardware over FILEIO vdisk
+iSCSI-SCST with default settings usually outperforms tuned IET a on
+3-10% (by default IET has not too good settings, so it shows
+considerably worse results) or has the similar performance. The bigger
+difference is expected with 10GbE hardware or with higher number of
+initiators, since iSCSI-SCST has less commands processing overhead per
+command, hence put less load on CPU. If you find a case where
+iSCSI-SCST has worse performance, than IET, please report it to SCST
+mailing list scst-devel@lists.sourceforge.net, it will be greatly
+appreciated.</li>
+</ul>
+<p>Also, in contrast to IET, iSCSI-SCST is open for any new
+development, modifications and improvements, so people who want to fix
+or implement something new will not have to keep and maintain separate
+patches as it is currently necessary with IET. ISCSI-SCST is going to
+be actively developed and gain in the future new features like support
+for multiple connections per session, error recovery levels &gt;0,
+etc., which eventually make it really "enterprise".<br>
+</p>
+<p>ISCSI-SCST is available for download from the <a
+ href="http://svn.sourceforge.net/scst">SCST SVN repository</a>. See
+above how to setup access to it.<br>
+</p>
+<p>After some testing for month-two, iSCSI-SCST is going to be fully
+released.<br>
+</p>
+<p>If you are an IET user, please, before installation carefully read
+README files of both iSCSI-SCST and the SCST core. Especially pay
+attention that now the LUN information for iSCSI-SCST is configured not
+using iscsi-scstd.conf file in /etc, but using corresponding SCST
+facilities. This is because now the responsibilities are divided (as it
+should be) between the target driver (iSCSI-SCST) and the SCST core.
+The target driver is responsible for handling targets and their
+parameters, SCST core is responsible for handling backstorage.<br>
+</p>
+</div>
 <hr
  style="width: 100%; height: 2px; margin-left: 0px; margin-right: 0px;">
 <h1><small>Target driver for QLogic 2200/2300 cards<br>
@@ -231,7 +329,7 @@ to it.<br>
 <h1><small>Target driver for LSI/MPT cards</small></h1>
 Target driver LSI/MPT cards was originally developed by Hu Gang, then
 Erik Habbinga has continued the development. This driver is on the
-alpha stage and available from the <a
+alpha stage and available for download from the <a
  href="http://svn.sourceforge.net/scst">SCST SVN repository</a>. See
 above how to setup access to it.<br>
 <br>
@@ -257,7 +355,7 @@ One major difference of this driver from the above target driver for
 QLogic 2200/2300 cards is that it supports 24xx series of chipsets.<br>
 <br>
 This driver is unstable and on the
-alpha stage. It is available from the <a
+alpha stage. It is available for download from the <a
  href="http://svn.sourceforge.net/scst">SCST SVN repository</a>. See
 above how to setup access to it.<br>
 <br>