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<h1 class="topictitle1">Example: Manage tape resources</h1>
<div><p>This topic provides an example of how to manage tape resources.</p>
<div class="section"><p>Each system in the following example reports two tape subsystems,
or resources. These tape resources are connected to the tape library resource.
In this example, the tape library resource is the 3494 Data Server. The 3494
Data Server then generates an automatic configuration of a device description
for a media library device (MLD) . In this situation, any request to the tape
library device (the 3494 Data Server) results in the tape library resource
manager allocating which tape resource to use. This simplifies tape management
tasks for most users because the system is responsible for the majority of
those tasks.</p>
<div class="note"><span class="notetitle">Note:</span> Users with multiple systems and limited attachment capabilities
might still need to force the use of specific resources.</div>
<p>The Work
with Media Library Status (WRKMBLSTS) command allows you to view the tape
libraries and associated tape resources from a configuration standpoint. Using
this command on each of the three systems in the example results in the following
displays:</p>
<div class="fignone"><span class="figcap">Figure 1. View of tape library TAPMLB01 from System A</span><br /><img src="rzam4001.gif" alt="View of tape library TAPMLB01 from System A. The system recognizes both TAPE01 and TAPE02. They are in an UNPROTECTED state." /><br /></div>
<div class="fignone"><span class="figcap">Figure 2. View of tape library TAPMLB01 from System A</span><br /><img src="rzam4001.gif" alt="View of tape library TAPMLB01 from System A. The system recognizes both TAPE01 and TAPE02. They are in an UNPROTECTED state." /><br /></div>
<div class="fignone"><span class="figcap">Figure 3. View of tape library TAPMLB01 from System A</span><br /><img src="rzam4001.gif" alt="View of tape library TAPMLB01 from System A. The system recognizes both TAPE01 and TAPE02. They are in an UNPROTECTED state." /><br /></div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzam4tape.htm" title="This topic describes the advantages and limitations of using tape for storage. It makes some recommendations about when tape is a good choice and when you should consider other media. It also provides planning, setup, management, and troubleshooting information for stand-alone tape devices and tape libraries.">Tape</a></div>
</div>
<div class="relref"><strong>Related reference</strong><br />
<div><a href="../cl/wrkmlbsts.htm">Work with Media Library Status (WRKMBLSTS)</a></div>
</div>
<div class="relinfo"><strong>Related information</strong><br />
<div><a href="../books/sc415345.pdf" target="_blank">Backup Recovery and Media Services for iSeries</a></div>
</div>
</div><div class="nested1" xml:lang="en-us" id="viewtapelibtapmlb01sysb"><a name="viewtapelibtapmlb01sysb"><!-- --></a><h2 class="topictitle2">View of tape library TAPMLB01 from System B</h2>
<div><div class="section"><br /><img src="rzam4002.gif" alt="View of tape library TAPMLB01 from System B. The system only recognizes TAPE01. TAPE01 is in an UNPROTECTED state." /><br /></div>
</div>
</div>
<div class="nested1" xml:lang="en-us" id="viewtapelibtapmlb01sysc"><a name="viewtapelibtapmlb01sysc"><!-- --></a><h2 class="topictitle2">View of tape library TAPMLB01 from System C</h2>
<div><div class="section"><br /><img src="rzam4003.gif" alt="View of tape library TAPMLB01 from System C. The systm only recognizes TAPE02. TAPE02 is in an UNPROTECTED state." /><br /><p>There are three possible
values for the allocation of each resource. Each value assumes that the tape
library is varied on. The values are:</p>
<dl><dt class="dlterm">ALLOCATED</dt>
<dd>An allocated resource is assigned to a particular system and no other
system can access it. The allocated state is analogous to a stand-alone device
that is varied on with the value ASSIGN(*YES).)</dd>
<dt class="dlterm">UNPROTECTED</dt>
<dd>An unprotected tape resource is not assigned to a particular system and
is available to respond to requests to its tape library device. This unprotected
state is analogous to a stand-alone device that is varied on with the value
ASSIGN(*NO). If a request is made to the tape library device and the tape
resource is selected by the tape library device resource manager, the tape
resource is assigned while it is being used.</dd>
<dt class="dlterm">DEALLOCATED</dt>
<dd>A deallocated tape resource is not assigned to a particular system and
is unavailable to respond to requests to its tape library device. If the tape
library is varied off, all of its tape resources are deallocated. The deallocated
state allows the use of a tape resource in stand-alone mode. It also allows
temporary use of a tape resource if a malfunction occurs with the robotic
components of the tape library.</dd>
</dl>
<p>When a tape resource that is shared between systems is not
in use, it should remain in an unprotected state with the tape library device
varied on. If the tape resource is left in an allocated or deallocated state,
a command request to use the resource might result in an error stating that
no resources are available.</p>
<p>If you are using backup and recovery media
services (BRMS), you should not use SHARED *YES for media libraries. Use UNPROTECTED
to share your resources. You can also use a combination of UNPROTECTED and
ALLOCATED on the network to ensure that each system has the correct device
that is required for backup operations. Leave the tape libraries varied on
at all times, and use the allocation status to control use.</p>
</div>
</div>
</div>
<div class="nested1" xml:lang="en-us" id="forceusespecificresources"><a name="forceusespecificresources"><!-- --></a><h2 class="topictitle2">Force use of specific resources</h2>
<div><div class="section"><p>One problem to consider in the example is the problem of cable
limitations. One system can potentially prevent another from accessing tape
resources even when one is available. The difference is in how a user can
force a system to use a specific resource. The ways to force a system to use
a specific resource are:</p>
<ul><li><a href="#schedule">Schedule jobs based on time</a></li>
<li><a href="#allocated">Use the resource selection sequence</a> </li>
<li><a href="#multiple">Use multiple tape library device descriptions</a> </li>
</ul>
</div>
</div>
</div>
<div class="nested1" xml:lang="en-us" id="schedule"><a name="schedule"><!-- --></a><h2 class="topictitle2">Schedule jobs based on time</h2>
<div><div class="section"><p>One method of resolving this problem is to manipulate the start
times of save operations on each system. In the example, system A and system
B are contending for tape resource TAP01. Start the save operation on system
B to ensure that system B has access to a tape resource.</p>
<p>The following
table shows how the strategy chart appears if this method is used in the example.</p>
<div class="tablenoborder"><a name="schedule__schtimeman"><!-- --></a><table cellpadding="4" cellspacing="0" summary="" id="schedule__schtimeman" frame="border" border="1" rules="all"><caption>Table 1. Schedule to meet system and device constraints using
time management</caption><thead align="left"><tr><th valign="top" id="d0e122">Start time</th>
<th valign="top" id="d0e124">Approximate complete time</th>
<th valign="top" id="d0e126">Backup group</th>
<th valign="top" id="d0e128">System</th>
<th valign="top" id="d0e130">Device</th>
<th valign="top" id="d0e132">Tape resource forced</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e122 ">10:05 p.m.</td>
<td valign="top" headers="d0e124 ">1:00 a.m.</td>
<td valign="top" headers="d0e126 ">2</td>
<td valign="top" headers="d0e128 ">A</td>
<td valign="top" headers="d0e130 ">TAPMLB01</td>
<td valign="top" headers="d0e132 ">TAP01 (TAP02 is busy on system C)</td>
</tr>
<tr><td valign="top" headers="d0e122 ">10:00 p.m.</td>
<td valign="top" headers="d0e124 ">11:00 p.m.</td>
<td valign="top" headers="d0e126 ">5</td>
<td valign="top" headers="d0e128 ">C</td>
<td valign="top" headers="d0e130 ">TAPMLB01</td>
<td valign="top" headers="d0e132 ">TAP02</td>
</tr>
<tr><td valign="top" headers="d0e122 ">11:00 p.m.</td>
<td valign="top" headers="d0e124 ">1:00 a.m.</td>
<td valign="top" headers="d0e126 ">6</td>
<td valign="top" headers="d0e128 ">C</td>
<td valign="top" headers="d0e130 ">TAPMLB01</td>
<td valign="top" headers="d0e132 ">TAP02</td>
</tr>
<tr><td valign="top" headers="d0e122 ">1:05 a.m.</td>
<td valign="top" headers="d0e124 ">6:00 a.m.</td>
<td valign="top" headers="d0e126 ">1</td>
<td valign="top" headers="d0e128 ">A</td>
<td valign="top" headers="d0e130 ">TAPMLB01</td>
<td valign="top" headers="d0e132 ">TAP02 (TAP01 is busy on system B)</td>
</tr>
<tr><td valign="top" headers="d0e122 ">1:00 a.m.</td>
<td valign="top" headers="d0e124 ">4:00 a.m.</td>
<td valign="top" headers="d0e126 ">3</td>
<td valign="top" headers="d0e128 ">B</td>
<td valign="top" headers="d0e130 ">TAPMLB01</td>
<td valign="top" headers="d0e132 ">TAP01</td>
</tr>
<tr><td valign="top" headers="d0e122 ">4:00 a.m.</td>
<td valign="top" headers="d0e124 ">:00 a.m.</td>
<td valign="top" headers="d0e126 ">4</td>
<td valign="top" headers="d0e128 ">B</td>
<td valign="top" headers="d0e130 ">TAPMLB01</td>
<td valign="top" headers="d0e132 ">TAP01</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</div>
<div class="nested1" xml:lang="en-us" id="allocated"><a name="allocated"><!-- --></a><h2 class="topictitle2">Use the resource selection sequence</h2>
<div><div class="section"><p>Because ALLOCATED resources are selected for use before UNPROTECTED
resources, you can use this aspect to your advantage. A user exit (the *EXIT
special value) is a user-defined CL command that permits automatic processing
of predefined user routines. On system A in the example, you can use the *EXIT
special value in the BRMS control group to change TAP02 from UNPROTECTED to
ALLOCATED. The next save request then attempts to access TAP02 first. When
the save operation is completed, you use the *EXIT special value at the end
of the control group to change the resource back from ALLOCATED to UNPROTECTED.
For more information about the *EXIT special value, see Backup Recovery and
Media Services for iSeries™.</p>
<p>In order to accomplish this in the
example, keep all the resources in UNPROTECTED status and change two backup
groups. In this situation, you are only concerned about systems that are attached
to more than one resource. Only systems that are attached to more than one
resource can produce a resource access conflict. In this example, the system
that is attached to more than one resource is System A, in <a href="#schedule__schtimeman">Table 1</a>. System A belongs to backup group 1 and backup group
2.</p>
</div>
<ol><li><span>Change Save backup group 2:</span><ol type="a"><li class="substepexpand"><span>Change TAP01 from *UNPROTECTED to *ALLOCATED by specify the
following command for the *EXIT special value:</span> <pre> VRYCFG CFGOBJ(TAPMLB01) CFGTYPE(*MLBRSC) STATUS(*ALLOCATE) RSRCNAME(TAP01)</pre>
</li>
<li class="substepexpand"><span>Perform the save operation.</span></li>
<li class="substepexpand"><span>Change TAP01 from *ALLOCATED to *UNPROTECTED by specifying the
following command for the *EXIT special value:</span> <pre>VRYCFG CFGOBJ(TAPMLB01) CFGTYPE(*MLBRSC) STATUS(*UNPROTECTED) RSRCNAME(TAP01)</pre>
</li>
</ol>
</li>
<li><span>Change Save backup group 1:</span><ol type="a"><li class="substepexpand"><span>Change TAP02 from *UNPROTECTED to *ALLOCATED by specifying the
following command for the *EXIT special value:</span> <pre> VRYCFG CFGOBJ(TAPMLB01) CFGTYPE(*MLBRSC) STATUS(*ALLOCATE) RSRCNAME(TAP02)</pre>
</li>
<li class="substepexpand"><span>Perform the save operation.</span></li>
<li class="substepexpand"><span>Change TAP02 from *ALLOCATED to *UNPROTECTED by specifying the
following command for the *EXIT special value:</span> <pre>VRYCFG CFGOBJ(TAPMLB01) CFGTYPE(*MLBRSC) STATUS(*UNPROTECTED) RSRCNAME(TAP02)</pre>
</li>
</ol>
</li>
</ol>
<div class="section"><p>The following table shows how the strategy table appears if this
method is used in the example.</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 2. Schedule to meet system and
device constraints using ALLOCATE before UNPROTECT</caption><thead align="left"><tr><th valign="top" id="d0e282">Start time</th>
<th valign="top" id="d0e284">Approximate complete time</th>
<th valign="top" id="d0e286">Backup group</th>
<th valign="top" id="d0e288">System</th>
<th valign="top" id="d0e290">Device</th>
<th valign="top" id="d0e292">Tape resource forced</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e282 ">10:00 p.m.</td>
<td valign="top" headers="d0e284 ">1:00 a.m.</td>
<td valign="top" headers="d0e286 ">2</td>
<td valign="top" headers="d0e288 ">A</td>
<td valign="top" headers="d0e290 ">TAPMLB01</td>
<td valign="top" headers="d0e292 ">TAP01</td>
</tr>
<tr><td valign="top" headers="d0e282 ">10:00 p.m.</td>
<td valign="top" headers="d0e284 ">11:00 p.m.</td>
<td valign="top" headers="d0e286 ">5</td>
<td valign="top" headers="d0e288 ">C</td>
<td valign="top" headers="d0e290 ">TAPMLB01</td>
<td valign="top" headers="d0e292 ">TAP02</td>
</tr>
<tr><td valign="top" headers="d0e282 ">11:00 p.m.</td>
<td valign="top" headers="d0e284 ">1:00 a.m.</td>
<td valign="top" headers="d0e286 ">6</td>
<td valign="top" headers="d0e288 ">C</td>
<td valign="top" headers="d0e290 ">TAPMLB01</td>
<td valign="top" headers="d0e292 ">TAP02</td>
</tr>
<tr><td valign="top" headers="d0e282 ">1:00 a.m.</td>
<td valign="top" headers="d0e284 ">6:00 a.m.</td>
<td valign="top" headers="d0e286 ">1</td>
<td valign="top" headers="d0e288 ">A</td>
<td valign="top" headers="d0e290 ">TAPMLB01</td>
<td valign="top" headers="d0e292 ">TAP02 (TAP01 is busy on system B)</td>
</tr>
<tr><td valign="top" headers="d0e282 ">1:00 a.m.</td>
<td valign="top" headers="d0e284 ">4:00 a.m.</td>
<td valign="top" headers="d0e286 ">3</td>
<td valign="top" headers="d0e288 ">B</td>
<td valign="top" headers="d0e290 ">TAPMLB01</td>
<td valign="top" headers="d0e292 ">TAP01</td>
</tr>
<tr><td valign="top" headers="d0e282 ">4:00 a.m.</td>
<td valign="top" headers="d0e284 ">6:00 a.m.</td>
<td valign="top" headers="d0e286 ">4</td>
<td valign="top" headers="d0e288 ">B</td>
<td valign="top" headers="d0e290 ">TAPMLB01</td>
<td valign="top" headers="d0e292 ">TAP01</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</div>
<div class="nested1" xml:lang="en-us" id="multiple"><a name="multiple"><!-- --></a><h2 class="topictitle2">Use multiple tape library device descriptions</h2>
<div><div class="section"><p>You can also use the multiple tape library device descriptions
that are created when a tape library is configured. As each tape resource
in a tape library reports to the iSeries server, a separate tape library
description might be created. Typically, you should use one TAPMLB <var class="varname">xx</var> and
assign all the tape resources to it. However, system A in the example differs
from this. The following display shows the configuration that is generated
on system A.</p>
<br /><img src="rzam4004.gif" alt="Both TAPMBL01 and TAPMLB02 are varied off" /><br /><p>After the command CFGDEVMLB(TAPMLB01) is completed,
you can see both resources under TAPMLB01, even though TAP02 actually generated
TAPMLB02. Both resources are set to UNPROTECTED.</p>
<br /><img src="rzam4005.gif" alt="You can see both resources under TAPMLB01, even though TAP02 actually generated TAPMLB02. Both resources are set to UNPROTECTED." /><br /><p>If you varied on TAPMLB02,
it also recognizes TAP01 and TAP02. However, because only one tape library
can use a resource, TAP01 and TAP02 must to be set to DEALLOCATED in TAPMLB02,
as is shown on the following display.</p>
<br /><img src="rzam4006.gif" alt="TAPMLB02 is varied on. It recognizes TAP01 and TAP02. Because only one tape library can use a resource, TAP01 and TAP02 must to be set to DEALLOCATED in TAPMLB02." /><br /><p>In order to use the TAPMLB02
device description, you set TAP01 to UNPROTECTED in TAPMLB01 and you set TAP02
to UNPROTECTED in TAPMLB02, as is shown in the following display.</p>
<br /><img src="rzam4007.gif" alt="TAP01 is set to UNPROTECTED in TAPMLB01 and TAP02 is set to UNPROTECTED in TAPMLB02." /><br /><p>The following table shows
how the strategy chart appears if you use this method in the example.</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 3. Schedule to meet system and device constraints using multiple tape
library descriptions</caption><thead align="left"><tr><th valign="top" id="d0e410">Start time</th>
<th valign="top" id="d0e412">Approximate complete time</th>
<th valign="top" id="d0e414">Backup group</th>
<th valign="top" id="d0e416">System</th>
<th valign="top" id="d0e418">Device</th>
<th valign="top" id="d0e420">Tape resource forced</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e410 ">10:00 p.m.</td>
<td valign="top" headers="d0e412 ">1:00 a.m.</td>
<td valign="top" headers="d0e414 ">2</td>
<td valign="top" headers="d0e416 ">A</td>
<td valign="top" headers="d0e418 ">TAPMLB01</td>
<td valign="top" headers="d0e420 ">TAP01</td>
</tr>
<tr><td valign="top" headers="d0e410 ">10:00 p.m.</td>
<td valign="top" headers="d0e412 ">11:00 p.m.</td>
<td valign="top" headers="d0e414 ">5</td>
<td valign="top" headers="d0e416 ">C</td>
<td valign="top" headers="d0e418 ">TAPMLB02</td>
<td valign="top" headers="d0e420 ">TAP02</td>
</tr>
<tr><td valign="top" headers="d0e410 ">11:00 p.m.</td>
<td valign="top" headers="d0e412 ">1:00 a.m.</td>
<td valign="top" headers="d0e414 ">6</td>
<td valign="top" headers="d0e416 ">C</td>
<td valign="top" headers="d0e418 ">TAPMLB02</td>
<td valign="top" headers="d0e420 ">TAP02</td>
</tr>
<tr><td valign="top" headers="d0e410 ">1:00 a.m.</td>
<td valign="top" headers="d0e412 ">6:00 a.m.</td>
<td valign="top" headers="d0e414 ">1</td>
<td valign="top" headers="d0e416 ">A</td>
<td valign="top" headers="d0e418 ">TAPMLB02</td>
<td valign="top" headers="d0e420 ">TAP02</td>
</tr>
<tr><td valign="top" headers="d0e410 ">1:00 a.m.</td>
<td valign="top" headers="d0e412 ">4:00 a.m.</td>
<td valign="top" headers="d0e414 ">3</td>
<td valign="top" headers="d0e416 ">B</td>
<td valign="top" headers="d0e418 ">TAPMLB01</td>
<td valign="top" headers="d0e420 ">TAP01</td>
</tr>
<tr><td valign="top" headers="d0e410 ">4:00 a.m.</td>
<td valign="top" headers="d0e412 ">6:00 a.m.</td>
<td valign="top" headers="d0e414 ">4</td>
<td valign="top" headers="d0e416 ">B</td>
<td valign="top" headers="d0e418 ">TAPMLB01</td>
<td valign="top" headers="d0e420 ">TAP01</td>
</tr>
</tbody>
</table>
</div>
<div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
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