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HTML
179 lines
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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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<meta name="DC.Title" content="Optical media" />
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<meta name="DC.Relation" scheme="URI" content="../rzam4/rzam4tapevsoptical.htm" />
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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>Optical media</title>
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</head>
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<body id="rzaiu298"><a name="rzaiu298"><!-- --></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">Optical media</h1>
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<div><div class="section"><img src="./delta.gif" alt="Start of change" />
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 1. Consider using optical media as part of
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your save strategy</caption><thead align="left"><tr><th valign="top" width="26.767676767676768%" id="d0e25">Characteristic</th>
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<th valign="top" width="73.23232323232324%" id="d0e27">Comparison</th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" width="26.767676767676768%" headers="d0e25 ">Access to data</td>
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<td valign="top" width="73.23232323232324%" headers="d0e27 ">Optical devices are random access devices. File access
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is independent to the order in which the data is stored. Multiple users can
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access the same volume simultaneously.</td>
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</tr>
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<tr><td valign="top" width="26.767676767676768%" headers="d0e25 ">Data transfer rates</td>
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<td valign="top" width="73.23232323232324%" headers="d0e27 ">Data transfer rates for tape tend to be higher than
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for optical, particularly if you use tape drive compression.</td>
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</tr>
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<tr><td valign="top" width="26.767676767676768%" headers="d0e25 ">Durability</td>
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<td valign="top" width="73.23232323232324%" headers="d0e27 ">Optical media has a life span around 50 years. </td>
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</tr>
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<tr><td valign="top" width="26.767676767676768%" headers="d0e25 ">Archiving</td>
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<td valign="top" width="73.23232323232324%" headers="d0e27 ">Write Once Read Many (WORM) optical media is made for
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archiving. Each sector on the media can only be written to once, when creating
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and updating files and directories. When a file is changed or deleted, a new
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version of the file gets written, and the old version still exists on the
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media. This unique characteristic of never rewriting the same sector is that
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it allows all previous versions of every file to remain on the media.</td>
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</tr>
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<tr><td valign="top" width="26.767676767676768%" headers="d0e25 ">Transportability</td>
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<td valign="top" width="73.23232323232324%" headers="d0e27 ">DVD-RAM media created or written to on the iSeries™ can
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be read from any platform that supports the Universal Disk Format (UDF) file
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system. UDF is an industry standard file system.</td>
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</tr>
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</tbody>
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</table>
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</div>
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<img src="./deltaend.gif" alt="End of change" /></div>
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<div class="section"><h4 class="sectiontitle">How random storage mode affects save functions</h4><p>Optical
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devices use a random storage mode to save information. Optical devices use
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a hierarchical file structure when the server accesses files on the media.</p>
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<p>You
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may specify a path name for the optical file in the save operation beginning
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with the root directory. If you specify an asterisk (*), the server generates
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an optical file name in the root directory (/). If you specify an <samp class="codeph">'optical_directory_path_name/*'</samp>,
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the server generates an optical file name in the specified directory on the
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optical volume. If the directory does not exist, the server creates the directory.</p>
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<p>For
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example, if you specify <samp class="codeph">SAVLIB LIB(MYLIB) DEV(OPT01) OPTFILE('MYDIR/*')</samp>,
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the server creates the following optical file: <samp class="codeph">MYDIR/MYLIB</samp>.</p>
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<p>The
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server looks for active files on the optical media volume for the same file
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that you save currently. For example, you previously saved a SAVLIB to optical
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media. Now you run a new SAV command to the same media; the server ignores
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the SAVLIB files and does not report any active files for your SAV command.</p>
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<p>In
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general, the save operation looks for an active file that matches the pathname
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specified on the OPTFILE parameter. SAVSYS and options 21 and 22 of the SAVE
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menu look for any active file.</p>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 2. Checking for active files
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on optical media</caption><thead align="left"><tr><th valign="top" width="26.633165829145728%" id="d0e88">Consideration</th>
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<th valign="top" width="73.36683417085426%" id="d0e90">General information</th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" width="26.633165829145728%" headers="d0e88 ">CLEAR(*NONE) parameter</td>
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<td valign="top" width="73.36683417085426%" headers="d0e90 "><p>If you specify CLEAR(*NONE) on the save command,
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the server checks the optical media volume for active optical files. The server
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looks for active files with the same name and path as the specified optical
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file.</p>
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<p>If the server<span class="uicontrol"> finds</span> an optical file that
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is identical to the specified optical file, the server displays an inquiry
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message. You may respond to the message by cancelling the process, writing
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over the existing file on the volume, or inserting a new cartridge.</p>
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<p>If
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the server <span class="uicontrol">does not</span> find any active files and there
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is enough space on the optical volume, the server writes the files to the
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media. If the server does not find enough available space on the optical media
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volume, the server prompts you to insert a new media volume in the media device.</p>
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</td>
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</tr>
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<tr><td valign="top" width="26.633165829145728%" headers="d0e88 ">CLEAR(*ALL) parameter</td>
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<td valign="top" width="73.36683417085426%" headers="d0e90 "><p>The CLEAR(*ALL) parameter automatically clears all
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of the files on the optical media volume without prompting.</p>
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</td>
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</tr>
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<tr><td valign="top" width="26.633165829145728%" headers="d0e88 ">CLEAR(*AFTER) parameter</td>
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<td valign="top" width="73.36683417085426%" headers="d0e90 "><p>The CLEAR(*AFTER) parameter clears all the media
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volumes after the first volume. If the server encounters the specified optical
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file on the first volume, the server sends an inquiry message that allows
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you to either end the save operation or replace the file.</p>
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</td>
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</tr>
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<tr><td valign="top" width="26.633165829145728%" headers="d0e88 ">CLEAR(*REPLACE) parameter</td>
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<td valign="top" width="73.36683417085426%" headers="d0e90 "><p>The CLEAR(*REPLACE) parameter automatically replaces
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active data of the specified optical file on the media volumes.</p>
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</td>
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</tr>
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<tr><td valign="top" width="26.633165829145728%" headers="d0e88 ">Check for active files parameter on the GO SAVE command</td>
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<td valign="top" width="73.36683417085426%" headers="d0e90 "><p>During a GO SAVE command, menu option 21 or 22, or
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a SAVSYS command if the server detects an active file of the specified optical
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file, it displays message OPT1563 in the QSYSOPR message queue. During other
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save command operations, the server may display message OPT1260 depending
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on the value of the CLEAR parameter. If the server does not detect an active
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file of the specified optical file, the server checks for available space.
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If there is room to write the file, the server writes the file to the current
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volume in random mode. If there is not enough room, the server prompts you
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to insert another optical media volume into your optical device.</p>
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<p>During
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a GO SAVE command, menu option 21, you specify Y or N at the <span class="uicontrol">Check
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for active files</span> prompt to see if there are active files on your
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media volume. </p>
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<ul><li><span class="uicontrol">Check for active files: N option</span> <p>When you select
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the Check for active files: N option, the option forces the server to automatically
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overwrite all files on your DVD-RAM optical media.</p>
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</li>
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<li><span class="uicontrol">Check for active files: Y option</span> <p>When you select
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the Check for active files: Y option, the option forces the server to check
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for active files on your DVD-RAM optical media.</p>
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</li>
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</ul>
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</td>
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</tr>
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<tr><td valign="top" width="26.633165829145728%" headers="d0e88 ">SAVSYS command messages</td>
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<td valign="top" width="73.36683417085426%" headers="d0e90 "><p>When you run a SAVSYS command to an optical media
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volume, the server displays message <span class="uicontrol">OPT1503 - Optical volume contains
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active files</span> if there are active files on the optical media volume.
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You can either initialize the media with the Initialize Optical (INZOPT) command
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or you can specify CLEAR(*ALL) on the SAVSYS command to run an unattended
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save. </p>
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</td>
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</tr>
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</tbody>
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</table>
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</div>
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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="rzaiurzaiu102.htm">Choose your save media</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rzaiurzaiu102.htm">Choose your save media</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="../rzam4/rzam4tapevsoptical.htm">Comparison of offline storage</a></div>
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<div><a href="../rzam4/rzam4optical.htm">Optical storage</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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