92 lines
6.0 KiB
HTML
92 lines
6.0 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
<html lang="en-us" xml:lang="en-us">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<meta name="security" content="public" />
|
|
<meta name="Robots" content="index,follow" />
|
|
<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))' />
|
|
<meta name="DC.Type" content="concept" />
|
|
<meta name="DC.Title" content="Considerations for multipath disk units" />
|
|
<meta name="DC.Relation" scheme="URI" content="rzalystordet.htm" />
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 2002, 2006" />
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2002, 2006" />
|
|
<meta name="DC.Format" content="XHTML" />
|
|
<meta name="DC.Identifier" content="rzalymultipath" />
|
|
<meta name="DC.Language" content="en-us" />
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
|
<!-- US Government Users Restricted Rights -->
|
|
<!-- Use, duplication or disclosure restricted by -->
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
|
<title>Considerations for multipath disk units</title>
|
|
</head>
|
|
<body id="rzalymultipath"><a name="rzalymultipath"><!-- --></a>
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
|
<h1 class="topictitle1">Considerations for multipath disk units</h1>
|
|
<div><p>Multiple connections to the logical unit number (LUN) from the IOA processors
|
|
was implemented in V5R3, up to eight connections can be defined from multiple
|
|
input/output processors on an iSeries™ server to a single LUN in the
|
|
Enterprise Disk Storage. The Enterprise Disk Storage concurrently supports
|
|
diverse host systems over diverse attachment protocols. Data storage is allocated
|
|
among the attached host systems with the Enterprise Disk Storage Specialist,
|
|
a Web-based interface. Each connection for a multipath disk unit functions
|
|
independently. Several connections provide availability by allowing disk storage
|
|
to be utilized even if a single path fails.</p>
|
|
<p>When you use multipath disk units, you must consider the implications of
|
|
moving IOPs and multipath connections between nodes. You must not split multipath
|
|
connections between nodes, either by moving IOPs between logical partitions
|
|
or by switching expansion units between systems. If two different nodes both
|
|
have connections to the same LUN in the Enterprise Disk Storage, both nodes
|
|
might potentially overwrite data from the other node.</p>
|
|
<p>The following figure shows a logical partition configuration with multiple
|
|
paths configured correctly. Partition 0 (P0) has multiple paths defined from
|
|
two different IOPs to one LUN in the Enterprise Disk Storage. Partition 1
|
|
(P1) also has multiple paths defined from two different IOPs to a different
|
|
LUN in the Enterprise Disk Storage. The configuration would be incorrect if
|
|
each logical partition had defined connections to a single LUN. </p>
|
|
<br /><img src="rzaly506.gif" alt="Multiple connections from IOAs to disk units in the Enterprise Storage Server" /><br /><div class="p">The system enforces the following rules when you use multipath disk units
|
|
in a multiple-system environment:<ul><li>If you move an IOP with a multipath connection to a different logical
|
|
partition, you must also move all other IOPs with connections to the same
|
|
disk unit to the same logical partition.</li>
|
|
<li>When you make an expansion unit switchable, make sure that all multipath
|
|
connections to a disk unit will switch with the expansion unit.</li>
|
|
<li>When you configure a switchable independent disk pool, make sure that
|
|
all of the required IOPs for multipath disk units will switch with the independent
|
|
disk pool.</li>
|
|
</ul>
|
|
If a multipath configuration rule is violated, the system issues warnings
|
|
or errors to alert you of the condition. It is important to pay attention
|
|
when disk unit connections are reported missing. You want to prevent a situation
|
|
where a node might overwrite data on a LUN that belongs to another
|
|
node.</div>
|
|
<p>Disk unit connections might be missing for a variety of reasons, but especially
|
|
if one of the preceding rules has been violated. If a connection for a multipath
|
|
disk unit in a system or basic disk pool is found to be missing during an
|
|
IPL, a message is sent to the QSYSOPR message queue.</p>
|
|
<p>If a connection is missing, and you confirm that the connection has been
|
|
removed, you can update Hardware Service Manager (HSM) to remove that resource.
|
|
Hardware service manager is a tool for displaying and working with system
|
|
hardware from both a logical and a packaging viewpoint, an aid for debugging
|
|
Input/Output (I/O) processors and devices, and for fixing failing and missing
|
|
hardware. You can access Hardware Service Manager in System Service Tools
|
|
(SST) and Dedicated Service Tools (DST) by selecting the option to start a
|
|
service tool.</p>
|
|
<div class="note"><span class="notetitle">Note:</span> Multiple connections are not supported for a load source LUN in an Enterprise
|
|
Disk Storage from an eServer™ i5 model. </div>
|
|
<div class="section"><img src="./delta.gif" alt="Start of change" /><h4 class="sectiontitle">Change multipath disk unit</h4><p>Use the <a href="../apis/qyassdmo.htm">Start DASD Management
|
|
Operation (QYASSDMO) API</a> to remove the missing multiple-path disk units,
|
|
resulting in only one path.</p>
|
|
When there is a missing connection to a disk
|
|
unit this message Event EV0D0401, Event Code 1E, Message ID CPI096E appears
|
|
in your QSYSOPR message queue.<img src="./deltaend.gif" alt="End of change" /></div>
|
|
</div>
|
|
<div>
|
|
<div class="familylinks">
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzalystordet.htm">Disk storage concepts</a></div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html> |