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    10 <!DOCTYPE task

    11   PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

    12 <task id="GUID-3D8B134E-3C2F-5BAF-82AB-0AB786A5D22D" xml:lang="en"><title> Directory

    13 Cache Tutorial</title><shortdesc>Describes how to configure the directory cache in a FAT file system

    14 enabled drive. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>

    15 <prereq id="GUID-E3BEB74D-79C7-59A9-9366-CCD8B52DB7F8-GENID-1-7-1-14-1-1-9-1-7-1-7-1-3-1"><p>Before you start,

    16 you must: </p> <ul>

    17 <li id="GUID-41E9D4BC-974F-5046-8FC1-E3C67298C5AA"><p>have the knowledge of

    18 the <xref href="GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534.dita">FAT file system</xref>  </p> </li>

    19 <li id="GUID-2F012BA2-6AF2-56D6-852E-6042618ECD8F"><p>have the knowledge of

    20 the <xref href="GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534.dita#GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534/GUID-86BEEEF5-F4F0-50AD-AF29-0A0277455BDB">directory

    21 cache</xref>  </p> </li>

    22 <li id="GUID-88E374C2-B670-53DE-8677-7712ECE3EB8F"><p>have the knowledge of

    23 the <xref href="GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534.dita#GUID-AFFC4002-3A06-5458-A4D9-1E0AEDB8C534/GUID-7675348A-9D74-54DB-A09A-0537AD4D6CA5">global

    24 cache manager</xref>. </p> </li>

    25 </ul> </prereq>

    26 <context id="GUID-6799E3F3-353E-5C00-A38C-D32F888392AA-GENID-1-7-1-14-1-1-9-1-7-1-7-1-3-2"><p>The developers

    27 can configure the directory cache memory with a dynamic range. The memory

    28 allocation for directory cache on a drive depends on the available global

    29 cache memory. The global cache manager allocates memory to various cache memory

    30 on different drives. The directory cache for a drive can be configured with

    31 a dynamic range in the <filepath>estart.txt</filepath> file. The dynamic range

    32 configuration consists of two values : </p> <ol id="GUID-166C832A-5B33-5271-AABD-A56EC49A61A3">

    33 <li id="GUID-4191D5E1-0A2E-5C0D-B1C6-FE49F5C24CE4"><p> <codeph>FAT_DirCacheSizeMin</codeph> specifies

    34 the minimum size of global cache to be allocated to the directory cache on

    35 a drive. </p> </li>

    36 <li id="GUID-E6941E15-9549-56B8-8F62-7BAAAD7DD90D"><p> <codeph>FAT_DirCacheSizeMax</codeph> specifies

    37 the maximum size of the global cache to be allocated to the directory cache

    38 of a drive. </p> </li>

    39 </ol> <p>The minimum size of the directory cache is permanently reserved during

    40 the file server startup time. The maximum memory allocation depends on the

    41 available system memory and hence not guaranteed under low memory conditions. </p> <p>The

    42 size of the cache memory is specified in Kilobytes. The default value for

    43 both the parameters is 128 Kilobytes. </p> </context>

    44 <steps id="GUID-67EA65BE-4457-57F5-B4F1-6A7A2F41354D">

    45 <step id="GUID-EBD3AEBE-54CB-53AA-9014-E2378A857221"><cmd>Open the estart.txt

    46 file </cmd>

    47 <info><p>to configure the directory cache.</p> </info>

    48 </step>

    49 <step id="GUID-B24F2606-491F-5888-A025-3B5F0F3D4D9B"><cmd/>

    50 <info>Create a new entry for a drive, say for example drive D: </info>

    51 </step>

    52 <step id="GUID-015BE3C2-6891-5BFC-979B-EBC7CF7E4590"><cmd/>

    53 <info>Enter the minimum size of the directory cache to be allocated to the

    54 parameter <codeph>FAT_DirCacheSizeMin</codeph>  </info>

    55 <info>The value is specified in Kilobytes </info>

    56 </step>

    57 <step id="GUID-D6EF2F51-44D6-57EF-9614-6B7AB8D43848"><cmd/>

    58 <info>Enter the maximum size of the directory cache that can be allocated

    59 when available to the parameter <codeph>FAT_DirCacheSizeMax</codeph>  </info>

    60 <info>The value is specified in Kilobytes. </info>

    61 </step>

    62 <step id="GUID-6EE5BE56-FD6E-523D-947D-2DCA5D4C0191"><cmd/>

    63 <info>Repeat steps 2-4 for other drives. </info>

    64 </step>

    65 <step id="GUID-A98147EC-F076-5A27-B7D4-AAA0A87E70FC"><cmd/>

    66 <info>Save and close the estart.txt file </info>

    67 </step>

    68 <step id="GUID-9D9F272C-F1F1-58F4-AB8B-672AD09ECA16"><cmd/>

    69 <info>Build the ROM with the modified estart.txt file </info>

    70 </step>

    71 </steps>

    72 <example><p> The sample entry for drive D is shown below: </p><codeblock xml:space="preserve">[DriveD]

    73 FAT_DirCacheSizeMin  128

    74 FAT_DirCacheSizeMax  256</codeblock></example>

    75 </taskbody><related-links>

    76 <link href="GUID-DC0BF2A3-613B-595C-BF47-07F29E2A7893.dita"><linktext>Leaf Directory

    77 Cache Configuration                 Tutorial</linktext></link>

    78 </related-links></task>