The flash memory available in newer router platforms (at the very minimum the ISR routers and 37xx series) is capable of being used as a regular disk drive (for example, to store system logging information), but it might be formatted as a traditional Low-End File System (LEFS) flash card (more likely if the router was not manufactured recently). To change the flash card format to disk-like FAT32 format, use the format flash: privileged-level command (and don't forget to store the IOS image to another location before formatting the flash). After the format process is complete, you can create subdirectories on the flash: memory and use it as a regular disk device. A sample formatting operation is displayed below:
Format operation may take a while. Continue? [confirm]
Format operation will destroy all data in "flash:". Continue? [confirm]
Enter volume ID (up to 64 chars)[default flash]:
Current Low End File System flash card in flash will be formatted into DOS File System flash card!
Continue? [confirm] y
Format: Drive communication & 1st Sector Write OK...
Writing Monlib sectors.
Monlib write complete
Format: All system sectors written. OK...
Format: Total sectors in formatted partition: 125297
Format: Total bytes in formatted partition: 64152064
Format: Operation completed successfully.
Format of flash complete
fw#show file system | include flash
* 64012288 27734016 disk rw flash:#