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  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">
<task id="GUID-3D8B134E-3C2F-5BAF-82AB-0AB786A5D22D" xml:lang="en"><title> Directory
Cache Tutorial</title><shortdesc>Describes how to configure the directory cache in a FAT file system
enabled drive. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
<prereq id="GUID-E3BEB74D-79C7-59A9-9366-CCD8B52DB7F8-GENID-1-12-1-18-1-1-10-1-7-1-7-1-3-1"><p>Before you start,
you must: </p> <ul>
<li id="GUID-41E9D4BC-974F-5046-8FC1-E3C67298C5AA"><p>have the knowledge of
the <xref href="GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534.dita">FAT file system</xref>  </p> </li>
<li id="GUID-2F012BA2-6AF2-56D6-852E-6042618ECD8F"><p>have the knowledge of
the <xref href="GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534.dita#GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534/GUID-86BEEEF5-F4F0-50AD-AF29-0A0277455BDB">directory
cache</xref>  </p> </li>
<li id="GUID-88E374C2-B670-53DE-8677-7712ECE3EB8F"><p>have the knowledge of
the <xref href="GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534.dita#GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534/GUID-7675348A-9D74-54DB-A09A-0537AD4D6CA5">global
cache manager</xref>. </p> </li>
</ul> </prereq>
<context id="GUID-6799E3F3-353E-5C00-A38C-D32F888392AA-GENID-1-12-1-18-1-1-10-1-7-1-7-1-3-2"><p>The developers
can configure the directory cache memory with a dynamic range. The memory
allocation for directory cache on a drive depends on the available global
cache memory. The global cache manager allocates memory to various cache memory
on different drives. The directory cache for a drive can be configured with
a dynamic range in the <filepath>estart.txt</filepath> file. The dynamic range
configuration consists of two values : </p> <ol id="GUID-166C832A-5B33-5271-AABD-A56EC49A61A3">
<li id="GUID-4191D5E1-0A2E-5C0D-B1C6-FE49F5C24CE4"><p> <codeph>FAT_DirCacheSizeMin</codeph> specifies
the minimum size of global cache to be allocated to the directory cache on
a drive. </p> </li>
<li id="GUID-E6941E15-9549-56B8-8F62-7BAAAD7DD90D"><p> <codeph>FAT_DirCacheSizeMax</codeph> specifies
the maximum size of the global cache to be allocated to the directory cache
of a drive. </p> </li>
</ol> <p>The minimum size of the directory cache is permanently reserved during
the file server startup time. The maximum memory allocation depends on the
available system memory and hence not guaranteed under low memory conditions. </p> <p>The
size of the cache memory is specified in Kilobytes. The default value for
both the parameters is 128 Kilobytes. </p> </context>
<steps id="GUID-67EA65BE-4457-57F5-B4F1-6A7A2F41354D">
<step id="GUID-EBD3AEBE-54CB-53AA-9014-E2378A857221"><cmd>Open the estart.txt
file </cmd>
<info><p>to configure the directory cache.</p> </info>
</step>
<step id="GUID-B24F2606-491F-5888-A025-3B5F0F3D4D9B"><cmd/>
<info>Create a new entry for a drive, say for example drive D: </info>
</step>
<step id="GUID-015BE3C2-6891-5BFC-979B-EBC7CF7E4590"><cmd/>
<info>Enter the minimum size of the directory cache to be allocated to the
parameter <codeph>FAT_DirCacheSizeMin</codeph>  </info>
<info>The value is specified in Kilobytes </info>
</step>
<step id="GUID-D6EF2F51-44D6-57EF-9614-6B7AB8D43848"><cmd/>
<info>Enter the maximum size of the directory cache that can be allocated
when available to the parameter <codeph>FAT_DirCacheSizeMax</codeph>  </info>
<info>The value is specified in Kilobytes. </info>
</step>
<step id="GUID-6EE5BE56-FD6E-523D-947D-2DCA5D4C0191"><cmd/>
<info>Repeat steps 2-4 for other drives. </info>
</step>
<step id="GUID-A98147EC-F076-5A27-B7D4-AAA0A87E70FC"><cmd/>
<info>Save and close the estart.txt file </info>
</step>
<step id="GUID-9D9F272C-F1F1-58F4-AB8B-672AD09ECA16"><cmd/>
<info>Build the ROM with the modified estart.txt file </info>
</step>
</steps>
<example><p> The sample entry for drive D is shown below: </p><codeblock xml:space="preserve">[DriveD]
FAT_DirCacheSizeMin  128
FAT_DirCacheSizeMax  256</codeblock></example>
</taskbody><related-links>
<link href="GUID-DC0BF2A3-613B-595C-BF47-07F29E2A7893.dita"><linktext>Leaf Directory
Cache Configuration                 Tutorial</linktext></link>
</related-links></task>