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<h1 class="topictitle1">How to use the shared, read-only storage space</h1>
<div><p>Learn how to read data from a shared storage space.</p>
<div class="p"><p>Version 5 Release 2 added the ability for multiple Linux partitions
to share virtual disks. Multiple partitions can now read data from a shared
storage space concurrently. The ability to share virtual disks is useful whenever
two or more Linux partitions need to use the same file. For example:</p>
<ul><li>Two or more Linux partitions used as Web servers could point to the same
Web page.</li>
<li>Two or more Linux partitions could want to read documentation from the
same file.</li>
<li>Two or more Linux partitions could want to run the same copy of an Apache
Web server program.</li>
</ul>
</div>
<div class="section">To use the storage space, you must link to the virtual disk and provide
users access. Use either of the following methods to use shared, read-only
storage:</div>
</div>
<div class="nested1" xml:lang="en-us" id="inav"><a name="inav"><!-- --></a><h2 class="topictitle2">Use the iSeries Navigator</h2>
<div><div class="section">To link a disk drive using iSeries™ Navigator, follow these steps:</div>
<ol><li><span>Click <span class="menucascade"><span class="uicontrol">Network</span></span><span class="menucascade"><span class="uicontrol">Windows Administration</span></span><span class="menucascade"><span class="uicontrol">Disk
Drives</span></span>.</span></li>
<li><span>Right-click an available disk drive and select <span class="uicontrol">Add Link</span>.</span></li>
<li><span>Select the server that you want to link the disk to.</span></li>
<li><span>Select one of the available link types and the link sequence position.</span></li>
<li><span>Select the <span class="uicontrol">Shared - Read</span> access type.</span></li>
<li><span>Click <span class="uicontrol">OK</span>.</span></li>
</ol>
</div>
</div>
<div class="nested1" xml:lang="en-us" id="clcommand"><a name="clcommand"><!-- --></a><h2 class="topictitle2">Use the Add Network Server Storage Link command</h2>
<div><div class="section">To link a disk drive using the Add Network Server Storage Link command,
follow these instructions:</div>
<ol><li class="stepexpand"><span>Type the Add Network Server Storage Link (ADDNWSSTGL) command. </span> The storage link for virtual disks that Linux partitions are going to
share concurrently must have an access type of read (*READ). <br /><img src="rzalm033.gif" alt="Add Network Server Storage Link display" /><br /><p>On the Add Network Server
Storage Link (ADDNWSSTGL) display, the value you enter in the Dynamic storage
link field can be either *YES or *NO. To display the Access option, press
the F9 key. If multiple Linux partitions share disks, the partitions must
access (that is, mount) the disks from Linux with read-only access.</p>
</li>
<li class="stepexpand"><span>You can specify that Linux has read-only access to the disk two
ways:</span><ul><li>By using an option on the mount command</li>
<li>By specifying read-only as a parameter in the /etc/fstab file</li>
</ul>
</li>
</ol>
<div class="example">The following is an example of the using the mount command to mount
a file system as read-only:<blockquote><pre>mount -o ro /dev/hdb1 /mnt/data2</pre>
</blockquote>
<p>An
entry in the /etc/fstab file to mount a disk resource as read-only would resemble
the following:</p>
<blockquote><pre>/dev/hdb1 /mnt/data ext2 ro 1 1</pre>
</blockquote>
</div>
</div>
<div class="nested2" xml:lang="en-us" id="update"><a name="update"><!-- --></a><h3 class="topictitle3">Update and provide users access</h3>
<div><div class="section">To update a shared storage space and provide users access, follow
these steps:</div>
<ol><li><span>Give all users <kbd class="userinput">*SHRUPD</kbd> access to the storage
space.</span></li>
<li><span>Have all users open the storage space concurrently for read-only
access.</span></li>
<li><span>Have all users stop accessing the data on that storage space and
close (unmount) that device from within Linux.</span></li>
<li><span>Have one user open the device for read-write access, update the
data, and close the device.</span></li>
<li><span>Have all users reopen the device for read-only concurrent access.</span></li>
</ol>
<div class="section">Other restrictions:<ul><li>Version 5 Release 2 or later of i5/OS<sup>®</sup> is required, but it
does not have to be in the primary partition.</li>
<li>The maximum size supported for a storage space is 1000 GB.</li>
<li>The maximum number of storage spaces supported is 64. However, while 64
storage spaces may be linked to the server, only the first 20 storage spaces
are visible to Linux, depending on the Linux distribution.</li>
</ul>
</div>
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