Cisco IOS Cookbook, 2nd Edition

Partitioning Flash

Problem

You want to change how your router’s flash memory is partitioned.

Solution

The partition command allows you to create a partition in the router’s flash memory:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#partition slot1: 2 8 8 
Router1(config)#end
Router1#

Discussion

As we discussed in Recipe 1.11, the erase command deletes the entire contents of a flash device. On routers that don’t support the delete and squeeze commands, there is no way to delete an individual file from flash without erasing all of the files in the flash device. Fortunately, you can use the partition command on flash devices to shelter some files from the effects of the erase command.

After you have partitioned a flash device, the erase command only affects one partition at a time. This command doesn’t affect any of the other partitions on the same flash device. You can use it to allow you to delete individual files without having to wipe out the entire flash device.

In the next example, we partitioned a flash device into two equal parts. We then stored an IOS image on each of the partitions. You can see the partitions and their contents with the following command:

Router1#show slot1: PCMCIA Slot1 flash directory, partition 1: File Length Name/status 1 7723664 c3620-ajs56i-mz.120-25.bin [7723728 bytes used, 664880 available, 8388608 total] 8192K bytes of processor board PCMCIA Slot1 flash (Read/Write) PCMCIA Slot1 flash directory, partition ...