76 lines
4.5 KiB
HTML
76 lines
4.5 KiB
HTML
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<meta name="DC.Title" content="Media capacity and volume threshold" />
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<meta name="abstract" content="Read about indicating a volume threshold for your applications." />
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<title>Media capacity and volume threshold</title>
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</head>
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<body id="capacitythreshold"><a name="capacitythreshold"><!-- --></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">Media capacity and volume threshold</h1>
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<div><p>Read about indicating a volume threshold for your applications.</p>
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<div class="p"><p>One thing to consider when writing to optical media is the possibility
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of reaching the media capacity or threshold. The optical file system provides
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a logical threshold capability to help applications protect themselves from
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reaching the absolute volume capacity. The logical threshold is defined when
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the volume initializes, and is unique for each volume. You can change this
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threshold by using the Change Optical Volume command.</p>
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<div class="note"><span class="notetitle">Note:</span> The logical
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volume threshold is only applicable for the high performance optical file
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system (HPOFS) media format. For UDF media format, the logical volume threshold
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is always 100% and cannot be changed.</div>
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<div class="p">You should devise
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a strategy to deal with the situation when the media becomes full. This is
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especially true when writing to WORM media. You might consider the following
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questions: <ul><li>How should I use the volume threshold?</li>
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<li>What should I do when the volume is full?</li>
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<li>How can I prepare for a volume-full condition?</li>
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</ul>
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</div>
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<p>The logical volume threshold is only applicable for high performance
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optical file system (HPOFS) media format. For UDF media format, the logical
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volume threshold is always 100% and cannot be changed.</p>
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<p>The volume threshold
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is provided to allow applications to prepare for an actual volume-full condition.
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When WORM media becomes full, there can be no further write operations.
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Depending on the requirements of the application, the threshold can be used
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in various ways to prepare for the media becoming physically full.</p>
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<p>For
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example, an application might write groups of spooled files to optical disk.
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After each group is written, an additional file might be written that contains
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an index to the spooled files just written. Without the index, the spooled
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files could be useless. Unless the application can manage the media capacity,
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the volume might run out of space before the index file can be written. One
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way to avoid running out of space is to set the volume threshold to 99%. When
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the message <kbd class="userinput">No space available</kbd> is issued, the application
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can then increase the threshold to 100% and write any necessary additional
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files.</p>
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</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="tipsandtechniques.htm" title="The following techniques are often helpful in designing custom optical programs for your business.">Tips: Optical programming</a></div>
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</div>
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</div>
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</body>
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