Magento File-Cache Backend Options

local.xml

<?xml version="1.0"?>
<config>
    <global>

        <!-- Add cache backend options to your local.xml file in app/etc -->
        <!-- BEGIN -->
        <cache>
            <backend_options>
                <hashed_directory_level>1</hashed_directory_level>
                <hashed_directory_umask>0777</hashed_directory_umask>
                <file_name_prefix>mage</file_name_prefix>
                <cache_file_umask>0777</cache_file_umask>
            </backend_options>
        </cache>
        <!-- END -->

    </global>
</config>