| 5.2 |  | Managing the Cisco File System |
| 5.2.8 |  | File system verification |

| There are several commands that can be used to verify the router file system. One of those is the show version command. The show version command can be used to check the current image and the total amount of flash. It also verifies two other items concerning loading the IOS. It identifies the source of the IOS image that the router used to boot and displays the configuration register. The boot field setting of the configuration register can be examined to determine from where the router is to load the IOS. If these do not agree, there may be a corrupt or missing IOS image in flash or there may be boot system commands in the startup configuration. The show flash command can also be used to verify the file system. This command is used to identify IOS image(s) in flash as well as the amount of flash that is available. This command is often used to confirm that there is ample space to store a new IOS image. As previously mentioned, the configuration file may contain boot system commands. These commands can be used to identify the source of the desired IOS boot image. Multiple boot system commands may be used to create a fallback sequence to discover and load an IOS. These boot system commands will be processed in the order of their appearance in the configuration file.