Flash File Systems
Overview
IOS Flash can have a number of differnet File system types depending on how the Flash has been formated.
'File System A' requires you to squeeze the filesystem to free up space once you delete a file. This is a pain. It also by default asks you 'do you want to erase flash?', every time you want to copy a file to flash, which can be little dangerous. The file system itself also more limited than the Class C version.
If have a IOS router using Class A, you can change it to use Class C file system by doing a format flash, (which of course deletes everything from flash.
How to tell if you are have a Class A or Class C file System?
Run the show file systems command.
A Class A will show the Flash type as Flash, while a Class C file system will show up the Flash Type as Disk.
Example below:
Class A File System Example
Router1#show file systems
File Systems:
Size(b) Free(b) Type Flags Prefixes
- - opaque rw archive:
- - opaque rw system:
- - opaque rw tmpsys:
- - opaque rw null:
- - network rw tftp:
* 64225276 11413684 flash rw flash:
245752 219371 nvram rw nvram:
- - opaque wo syslog:
- - opaque rw xmodem:
- - opaque rw ymodem:
- - network rw rcp:
- - network rw pram:
- - network rw ftp:
- - network rw http:
- - network rw scp:
- - opaque ro tar:
- - network rw https:
- - opaque ro cns:
Class B File System Example
Router2#sho file systems
File Systems:
Size(b) Free(b) Type Flags Prefixes
- - opaque rw archive:
- - opaque rw system:
- - opaque rw tmpsys:
- - opaque rw null:
- - network rw tftp:
* 64016384 11173888 disk rw flash:#
245752 220602 nvram rw nvram:
- - opaque wo syslog:
- - opaque rw xmodem:
- - opaque rw ymodem:
- - network rw rcp:
- - network rw pram:
- - network rw ftp:
- - network rw http:
- - network rw scp:
- - opaque ro tar:
- - network rw https:
- - opaque ro cns: