81 lines
5.3 KiB
HTML
81 lines
5.3 KiB
HTML
<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="dc.language" scheme="rfc1766" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<meta name="dc.date" scheme="iso8601" content="2005-09-13" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow"/>
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<title>Advanced iSCSI support</title>
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<link rel="stylesheet" type="text/css" href="ibmidwb.css" />
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<link rel="stylesheet" type="text/css" href="ic.css" />
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</head>
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<body>
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<a id="Top_Of_Page" name="Top_Of_Page"></a><!-- Java sync-link -->
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<script language = "Javascript" src = "../rzahg/synch.js" type="text/javascript"></script>
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<img src="delta.gif" alt="Start of change" /><img src="delta.gif" alt="Start of change" />
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<a name="rzahqadvancediscsihardware"></a>
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<h4 id="rzahqadvancediscsihardware">Advanced iSCSI support</h4>
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<p>A single iSCSI HBA for iSeries™ is capable of supporting several servers
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or hosted systems. Each hosted system is also capable of connecting to multiple
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iSCSI HBAs for iSeries. <a href="rzahqadvancediscsihardware.htm#rzahqfigiscsiadvan">Figure 8</a> illustrates
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a hosted system that is connected to more than one iSCSI HBA for iSeries.</p>
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<a name="rzahqfigiscsiadvan"></a>
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<div class="fignone" id="rzahqfigiscsiadvan"><img src="delta.gif" alt="Start of change" /><span class="figcap">Figure 8. Advanced configuration</span>
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<div class="mmobj">
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<img src="rzahq503.gif" alt="This image shows the network connections between i5/OS and a hosted system that has multiple iSCSI adapters installed." /></div><img src="deltaend.gif" alt="End of change" /></div>
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<p><a href="rzahqadvancediscsihardware.htm#rzahqfigiscsiadvan">Figure 8</a> shows multiple iSCSI HBAs installed in
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the hosted system.</p>
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<p><span class="bold">Path definition</span>
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<br /> When a hosted system
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is connected to an iSCSI HBA for iSeries a path is defined between the hosted
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system and the iSCSI HBA for iSeries.</p>
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<p>There are several distinct paths defined in <a href="rzahqadvancediscsihardware.htm#rzahqfigiscsiadvan">Figure 8</a>.
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These are labelled 1, 2 and M.</p>
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<p>A virtual device being hosted in an iSeries server is said to be found behind a
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path. A configured virtual disk (for example Drive C:) hosted in i5/OS™ by an iSCSI
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HBA for iSeries or NWSH adapter is found behind that NWSH adapter.</p>
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<p>In <a href="rzahqadvancediscsihardware.htm#rzahqfigiscsiadvan">Figure 8</a>, paths 1 and 2 are each defined for
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a separate iSCSI HBA for iSeries. Devices defined in path 1 can only
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be found behind the iSCSI adapter where the path is defined. Similarly, devices
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defined in path 2 can only be found behind the iSCSI adapter where the path
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is defined. Any devices defined behind path 1 or 2 are said to be found exclusively
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behind their specific iSCSI HBA.</p>
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<p><span class="bold">Introduction to multi-path</span>
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<br />A hosted system
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can have redundant paths to access virtual disks hosted by i5/OS. The most comprehensive
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case is when there are redundant paths at each end. A given virtual disk can
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be accessed from the hosted system using either of the two iSCSI HBAs installed
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in the hosted system and found in the iSeries using either one of the two iSCSI HBAs
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for iSeries. This is known as multi-path.</p>
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<p>In <a href="rzahqadvancediscsihardware.htm#rzahqfigiscsiadvan">Figure 8</a> the multi-path is defined as M. Virtual
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disks found behind the multi-path can be accessed by either one of the iSCSI
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HBAs that are installed in the iSeries server. A multi-path is defined as
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a group of iSCSI HBAs for iSeries that can access or use path M. Only
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one multi-path group can be defined per hosted system. This group can include
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more than one iSCSI HBA for iSeries.</p>
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<a name="wq13"></a>
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<div class="notetitle" id="wq13">Note:</div>
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<div class="notebody">Removable media devices can not be defined in a multi-path
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group.</div>
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<p><span class="bold">Dedicated Bandwidth</span>
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<br />There are cases where
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redundant paths may not be wanted or required, but virtual disks requiring
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higher performance may need a dedicated path.</p>
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<p>In <a href="rzahqadvancediscsihardware.htm#rzahqfigiscsiadvan">Figure 8</a>, a hosted system configuration can
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define a virtual disks behind path 1 or 2 instead behind of behind path M.
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This way, an iSCSI adapter's bandwidth can be dedicated to certain virtual
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disks.</p><img src="deltaend.gif" alt="End of change" /><img src="deltaend.gif" alt="End of change" />
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<a id="Bot_Of_Page" name="Bot_Of_Page"></a>
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</body>
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</html>
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