This document explains the difference between operational and locked
Flash on the Content Services Switch (CSS) 11000 and 11500.
For more information on document conventions, see the
Cisco Technical Tips
There are no specific prerequisites for this document.
This document is not restricted to specific software and hardware
The information presented in this document was created from devices in
a specific lab environment. All of the devices used in this document started
with a cleared (default) configuration. If you are working in a live network,
ensure that you understand the potential impact of any command before using
Flash memory is a type of sector-based electrically erasable
nonvolatile memory that can be erased and reprogrammed in units of memory.
Flash gets its name because the microchip is organized so that a section of
memory cells are erased in a single action or flash. CSS switches use a Flash
image to store the initial program code that the CPU executes when the switch
is powered up. This initial program loads the selected version of WebNS as
specified in the boot configuration records.
The CSS switch contains two Flash images on each unit. One image is
referred to as the operational Flash image, and the other is referred to as the
locked Flash image. The locked Flash image provides a recovery path if the
operational Flash is corrupted during automatic update. Both Flash images are
located in Flash ROM, however, they are stored in different segments on the
ROM. In theory, both images should not become corrupt. This Flash ROM is
non-volatile, which means that these images continue to be stored in this
physical locale when the system is powered down. Normally, when a CSS switch
reboots, it loads the operational Flash image from the Flash ROM, which
consists of the ROM Monitor (ROMmon), Diag Monitor, and OFFDM. The OFFDM then
loads the WebNS image from disk, PCMCIA memory or network.
A new version of code is loaded (a new .adi image), and the version
number indicates that it contains a newer operational Flash image then what is
resident in the Flash of the system. The unpacking process first writes the
operational Flash image on the disk or PCMCIA memory under the directory
/ap0x0x00x/images/ (CSS 11000) or /sg0x0x00x/images/ (CSS 11500). This is the
Flash image that is burned into the Flash.
If the CSS switch is not able to boot from the operational Flash image,
for example, it becomes corrupt, it will use the older locked Flash code that
was placed in Flash during the manufacturing of the unit. The locked Flash
image will provide the initial program so that the WebNS image can be loaded.
An older version of locked Flash will work correctly with the newer run-time
Note: An important thing to note is that there is no automatic update of
the locked Flash image. The switch will continue to boot from the locked Flash
image until the operational Flash image is restored by either manual
intervention (via OFFDM), or by loading a new .adi file.
The locked Flash image should never be upgraded or
removed. This could cause the unit to become incapacitated.
By issuing the CLI command version, you can
determine the version of operational and locked Flash images.
Version: sg0720310s (7.20 Build 310)
Flash (Locked): 7.10 Build 3
Flash (Operational): 7.30 Build 10
Licensed Cmd Set(s): Standard Feature Set
Enhanced Feature Set
The locked Flash image can also be viewed by issuing the CLI commands
show chassis and show chassis