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Recovering from Locked Blocks in Flash Memory Cards or Flash Disks
A locked block in Flash memory cards or Flash disks occurs when power is lost, or a Flash memory card
or Flash disk is unplugged during a write or erase operation. When a block of Flash memory is locked,
it cannot be written to or erased, and the operation will consistently fail at a particular block location.
The only way to recover from locked blocks is to reformat the Flash memory card or Flash disk with the
format command. (See the
Formatting a Flash memory card or Flash disk erases its data.
Caution
Recovering Lost Password
This section provides information on how to recover a lost password.
The following overview describes this process:
1.
2.
3.
A key to recovering a lost password is to set the configuration register so that the contents of NVRAM
Note
are ignored (0x0040), allowing you to see your password.
4.
5.
6.
Use the following procedure to recover a lost password.
Note
If the enable password is encrypted, the following password recovery procedure will not work and
you will have to reconfigure the system; you will not be able to reboot it. To reconfigure the system,
use the displayed configuration, which is shown using the show startup-config EXEC command.
(See
Attach an ASCII terminal to the GRP console port.
Step 1
Configure the terminal to operate at 9600 bps, 8 data bits, no parity, 2 stop bits (or to whatever settings
Step 2
the console port is set).
Enter the show version command to display the existing configuration register value. Note this value
Step 3
for later use.
If Break is disabled, power cycle the router. (To power cycle, turn off power, wait 5 seconds, then turn
Step 4
it on again.) If Break is enabled on the router, press the Break key or send a break by holding down the
Control key and pressing the right square bracket key (^]); then proceed to
Within 5 seconds of turning on the router, press the Break key. This action causes the terminal to
Step 5
display the bootstrap program prompt as follows:
rommon 1>
78-4339-09
"Formatting a Flash Memory Card or Flash Disk" section on page
Use the show version command to note the existing software configuration register value.
Break to the bootstrap program prompt.
Change the configuration register to ignore NVRAM.
Enter privileged level in the system EXEC.
Use the show startup-config command to display the enable password.
Change the configuration register value back to its original setting.
Step
11.)
Implementing Additional Configuration and Maintenance Tasks
Recovering Lost Password
37.)
Step
5.
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