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question on setting boot images

I have a couple of questions regarding upgrading of images on an ASA. I have read where you can set up to 4 images, but I can't see anywhere where they give you an example of the syntax. I know for a single image, the syntax would be something like "boot system disk0:/asa724-30-k8.bin" to boot a single image. So my first question is, let's say I wanted a backup image of 724-20-k8.bin code in case my primary 724-k8-bin failed, would the syntax be the same with simply a "/" in between them, or "boot system disk0:/asa724-30-k8-bin/asa724-20-k8.bin" or is that syntax wrong?

2nd question, I know you don't have to define a boot image and that the ASA will grab the first image it finds in flash and boot from it. So if I don't have a particular boot image set, yet I have multiple images in my flash, what method does the ASA use to determine which one it "finds first"?

lastly, when I manually set the image file to boot from with the boot system command, what happens if that image is corrupt, and I happen to have other images in flash? Will the ASA do what it does when there is no boot statement and just grab the next one it finds, or will it only try what is defined in the boot system statement?


Cisco Employee

Re: question on setting boot images


To specify multiple boot images, you simply add them each as a single line. For example:

asa(config)# boot system disk0:/asa805-k8.bin
asa(config)# boot system disk0:/asa821-k8.bin

If you don't set the boot variable, the ASA will simply parse through the flash and boot the first available image it finds. You can see the order it will follow in the output of 'sh flash'.

Finally, in the event that you configure an incorrect boot statement or try to explicitly load a corrupted image, the ASA will follow the same functionality as above and parse through list of available image files in flash. You'll see something like this at boot time:

unable to boot an image

Default configuration file contains 1 entry.

Searching / for images to boot.

Hope that helps.


Community Member

Re: question on setting boot images

perfect! thanks very much for the explanation!

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