72 lines
5.2 KiB
HTML
72 lines
5.2 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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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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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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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Tape labeling" />
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<meta name="abstract" content="Find out how tape on your system is labeled." />
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<meta name="description" content="Find out how tape on your system is labeled." />
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<meta name="DC.Relation" scheme="URI" content="concept.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="taplbl" />
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<meta name="DC.Language" 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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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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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>Tape labeling</title>
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</head>
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<body id="taplbl"><a name="taplbl"><!-- --></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">Tape labeling</h1>
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<div><p>Find out how tape on your system is labeled.</p>
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<p>The following series of diagrams provides a basic description of standard tape labeling used for the <span class="keyword">iSeries™</span> system.</p>
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<p>In <a href="#taplbl__rbahh526.eps">Figure 1</a>, the INZTAP command gives
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the tape a volume label (marked VOL1) and writes two tape marks (TM).</p>
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<div class="fignone" id="taplbl__rbahh526.eps"><a name="taplbl__rbahh526.eps"><!-- --></a><span class="figcap">Figure 1. Volume label and tape marks</span><br /><img src="rbahh526.gif" alt="As mentioned in the previous
sentence, this diagram displays a tape with a volume label of VOL1 and two
tape marks to the right of it labeled TM." /><br /></div>
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<p>When a high-level language program opens a tape file, the system does the
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following procedures:</p>
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<ol><li>Writes over the two tape marks that follow the VOL label with header labels
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HDR1 and HDR2</li>
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<li>Adds a single tape mark that follows the header labels</li>
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</ol>
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<p>Each header label is 80 bytes long. <span>The first header label contains</span> such
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information as the file name and date. <span>The second header label specifies</span> information
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such as record and block lengths, record block format, and buffer offset (for
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ASCII files).</p>
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<p>When a high-level language program writes data to tape the system writes
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the data to the tape after the tape mark. Reaching the end of the file the
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system writes a tape mark and two end-of-file labels on the tape. The end-of-file
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labels contain the same information as the header labels except that the first
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end-of-file label (EOF1) includes the block count for the file.</p>
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<p>Two tape marks follow the end-of-file labels as shown in the following
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diagram in <a href="#taplbl__rbahh521.eps">Figure 2</a></p>
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<div class="fignone" id="taplbl__rbahh521.eps"><a name="taplbl__rbahh521.eps"><!-- --></a><span class="figcap">Figure 2. End of file labels</span><br /><img src="rbahh521.gif" alt="This diagram shows two tape
files. The first tape file contains the following from left to right: VOL1
as a label, Header labels HDR1 and HDR2, a tape mark labeled TM and lastly
data. The end-of-file label includes the following from left to right: TM,
EOF1 and EOF2, TM and TM." /><br /></div>
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<p>When the high-level language program adds a second file to the tape, the
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system creates a header label (HDR1) for the new file. This header label (HDR1)
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for the new file writes over the second tape mark following the end-of-file
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labels. The second header label, another tape mark, and the file data follow
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the new header label (HDR1) as illustrated in the following figure. </p>
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<div class="fignone" id="taplbl__rbahh522.eps"><a name="taplbl__rbahh522.eps"><!-- --></a><span class="figcap">Figure 3. New header label</span><br /><img src="rbahh522.gif" alt="This graphic is described
in the above paragraph." /><br /></div>
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<p>When the tape drive reaches the end of the physical tape, the system writes
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two tape marks that follow the end-of-volume labels. If the file is not complete,
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it continues on a second volume, which specifies the tape as
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volume 2 of the file.</p>
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<div class="fignone"><br /><img src="rbahh523.gif" alt="This graphic is also described
in the paragraph above." /><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="concept.htm" title="Find out how tape files operate on your server.">Concepts</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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