- <td>Tells rEFInd what methods to use to locate boot loaders. The <tt>internal</tt>, <tt>external</tt>, and <tt>optical</tt> parameters tell rEFInd to scan for EFI boot loaders on internal, external, and optical (CD, DVD, and Blu-ray) devices, respectively. The <tt>hdbios</tt>, <tt>biosexternal</tt>, and <tt>cd</tt> parameters are similar, but scan for BIOS boot loaders. (Note that the BIOS options are likely to be useless on UEFI PCs.) The <tt>manual</tt> parameter tells rEFInd to scan the configuration file for manual settings. You can specify multiple parameters to have the program scan for multiple boot loader types. When you do so, the order determines the order in which the boot loaders appear in the menu. The default is <tt>internal, external, optical</tt>.</td>
+ <td>Tells rEFInd what methods to use to locate boot loaders. The <tt>internal</tt>, <tt>external</tt>, and <tt>optical</tt> parameters tell rEFInd to scan for EFI boot loaders on internal, external, and optical (CD, DVD, and Blu-ray) devices, respectively. The <tt>hdbios</tt>, <tt>biosexternal</tt>, and <tt>cd</tt> parameters are similar, but scan for BIOS boot loaders. (Note that the BIOS options scan more thoroughly and actively on Macs than on UEFI-based PCs; for the latter, only options in the firmware's boot list are scanned, as described on the <a href="using.html">Using rEFInd</a> page.) The <tt>manual</tt> parameter tells rEFInd to scan the configuration file for manual settings. You can specify multiple parameters to have the program scan for multiple boot loader types. When you do so, the order determines the order in which the boot loaders appear in the menu. The default is <tt>internal, external, optical, manual</tt> on most systems, but <tt>internal, hdbios, external, biosexternal, optical, cd, manual</tt> on Macs.</td>
+</tr>
+<tr>
+ <td><tt>scan_delay</tt></td>
+ <td>numeric (integer) value</td>
+ <td>Imposes a delay before rEFInd scans for disk devices. Ordinarily this is not necessary, but on some systems, some disks (particularly external drives and optical discs) can take a few seconds to become available. If some of your disks don't appear when rEFInd starts but they <i>do</i> appear when you press the Esc key to re-scan, try uncommenting this option and setting it to a modest value, such as <tt>2</tt>, <tt>5</tt>, or even <tt>10</tt>. The default is <tt>0</tt>.</td>