|  | 7.2 | Bootstrap Options in Software
| 7.2.3 | The show flash command
Use the show flash command to verify that you have sufficient memory on your system for the Cisco IOS software that you want to load. The example shows the router has 4 MB of Flash memory, all of which is free. Compare this with the length of the Cisco IOS software image. Sources for this image size may include the software order document or output from the configuration software application on the Cisco Connection Online (CCO) World Wide Web site or a command like dir or ls issued on your TFTP server. If there is insufficient free memory, you will not be able to copy or load the image, which means that you can either try to obtain a smaller Cisco IOS software image or increase the available memory on the router. It is a good idea to keep a backup copy of the IOS image file for each router. You will also want to always backup your current IOS before upgrading to a newer version. In this lab you will use a TFTP (Trivial File Transfer Protocol) server to act as a backup storage location for the IOS image.