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Managing Configuration Files Larger than NVRAM
To maintain a configuration file that exceeds the size of NVRAM (512 KB), you must compress or relocate the configuration
file. This section provides an example of each approach. For more information, refer to the Cisco IOS Configuration
Fundamentals Configuration Guide.
Compressing the Configuration File
Use the service compress-config global configuration command to compress the configuration file for storage in NVRAM. A
compressed file can take several minutes longer to load than an uncompressed file.
To compress configuration files, use the following commands, beginning in global configuration mode:
Step1 Specify that the configuration file is to be compressed.
Router(config)# service compress-config
Step2 Exit global configuration mode.
Router(config)# end
Step3 Use one of the copy commands to copy the new configuration, for example:
Router# copy running-config startup-config
Building configuration...
Compressing configuration from 129648 bytes to 11077 bytes
[OK]
To cancel the compression feature, use the no service compress-config command.
Note If you try to load a configuration that is more than three times larger than the NVRAM size, the following error message
appears: [buffer overflow—file-size/buffer-size bytes].
Relocating the Configuration to a Flash Disk
To run the startup configuration off a Flash disk, use the following commands beginning in privileged EXEC mode:
Step1 Copy the current startup configuration to a new location. In the following example, the configuration file is copied
from a TFTP server to a Flash disk in slot0:
Router# copy tftp://172.16.2.15/example-config disk0:router-config
Step2 Enter global configuration mode.
Router# configure terminal
Router(config)#
Step3 The buffer that holds the configuration file is usually the size of NVRAM (512 KB). Larger configurations need larger
buffers. Change the size of the buffer that holds the configuration commands.
Router(config)# boot buffersize 1024000
Step4 Specify that the startup configuration file is located in Flash memory by setting the CONFIG_FILE variable. In the
following example, the system is told that the boot configuration file is in slot 0 and the filename is router-config:
Router(config)# boot config disk0:router-config