89 lines
7.3 KiB
HTML
89 lines
7.3 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Network redundancy considerations for a distributed relational database" />
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<meta name="abstract" content="Network redundancy provides different ways for users on the distributed relational database network to access a relational database on the network." />
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<meta name="description" content="Network redundancy provides different ways for users on the distributed relational database network to access a relational database on the network." />
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<meta name="DC.subject" content="network redundancy, redundancy, communications network, command, WRKCFGSTS (Work with Configuration Status), Work with Configuration Status (WRKCFGSTS), command, CL, WRKCFGSTS (Work with Configuration Status), Work with Configuration Status (WRKCFGSTS), configuration status, working with, VRYCFG (Vary Configuration), Vary Configuration (VRYCFG), Vary Configuration (VRYCFG), configuration, varying" />
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<meta name="keywords" content="network redundancy, redundancy, communications network, command, WRKCFGSTS (Work with Configuration Status), Work with Configuration Status (WRKCFGSTS), command, CL, WRKCFGSTS (Work with Configuration Status), Work with Configuration Status (WRKCFGSTS), configuration status, working with, VRYCFG (Vary Configuration), Vary Configuration (VRYCFG), Vary Configuration (VRYCFG), configuration, varying" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Network redundancy considerations for a distributed relational database</title>
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</head>
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<body id="rbal1netredund"><a name="rbal1netredund"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Network redundancy considerations for a distributed relational database</h1>
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<div><p>Network redundancy provides different ways for users on the distributed
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relational database network to access a relational database on the network.</p>
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<p> If there is only one communications path from an application requester
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(AR) to an application server (AS), when the communications line is down,
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users on the AR do not have access to the AS relational database. For this
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reason, network redundancy considerations are important to the distributed
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relational database administrator for the Spiffy Corporation. For example,
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consider service booking or customer parts purchasing issues for a dealership.
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When a customer is waiting for service or to purchase a part, the service
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clerk needs access to all authorized tables of enterprise information to schedule
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work or sell parts.</p>
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<p>If the local server is down, no work can be done. If the local server is
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running but a request to a remote server is needed to process work and the
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remote server is down, the request can not be handled. In the Spiffy Corporation
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example, this might mean that a dealership cannot request parts information
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from a regional inventory center. Also, if an AS that handles many AR jobs
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is down, none of the ARs can complete their requests. In the case of the Spiffy
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Corporation network, if a regional center is down, none of the application
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servers it supports can order parts.</p>
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<p>Providing the region's dealerships with access to regional inventory data
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is important to the Spiffy Corporation distributed relational database administrator.
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Providing paths through the network to data can be addressed in several ways.
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The original network configuration for the Spiffy Corporation linked the end
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node dealerships to their respective network node regional centers.</p>
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<div class="fignone" id="rbal1netredund__rbal1netred"><a name="rbal1netredund__rbal1netred"><!-- --></a><span class="figcap">Figure 1. Alternative network paths</span><br /><img src="rv2w739.gif" alt="Alternative Network Paths" /><br /></div>
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<p>An alternative for some dealerships might be a switched-line connection
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to a different regional center. If the local regional center is unavailable
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to the network, access to another AS allows the requesting dealership to obtain
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information needed to do their work. In the first figure, some ARs served
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by the MP000 server establish links to the KC000 server, which can be used
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whenever the MP000 server is unavailable. The <span class="cmdname">Vary Configuration
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(VRYCFG)</span> or <span class="cmdname">Work with Configuration Status (WRKCFGSTS)</span> command
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can be used by a server operator or distributed relational database administrator
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to vary the line on when needed and vary the line off when the primary AS
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is available. </p>
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<p>Another alternative might be if one of the larger area dealerships also
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acted as an AS for other dealerships. As shown in the second figure, an end
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node is only an AS to other end nodes through its network node. In the first
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figure, if the link to Minneapolis is down, none of the dealerships can query
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another (end node) for inventory. The configuration illustrated above can
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be changed so that one of the dealerships is configured as an APPN network
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node, and lines to that dealership from other area dealerships are set up.</p>
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<div class="fignone" id="rbal1netredund__rbal1altas"><a name="rbal1netredund__rbal1altas"><!-- --></a><span class="figcap">Figure 2. Alternate application server</span><br /><div class="imageleft"><img src="rv2w744.gif" alt="Alternate Application Server" /></div><br /></div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbal1recover.htm" title="In a distributed relational database environment, data availability not only involves protecting data on an individual server in the network, but also ensuring that users have access to the data across the network.">Data availability and protection</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../cl/vrycfg.htm">Vary Configuration (VRYCFG) command</a></div>
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<div><a href="../cl/wrkcfgsts.htm">Work with Configuration Status (WRKCFGSTS) command</a></div>
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</div>
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</div>
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</body>
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</html>
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