Minimum Flash requirement for IOS image

May 18, 2010 2 Replies
R

image: IP c3620-i-mz.123-26.bin Release Date: 18/Mar/2008 Size: 8031.25 KB (8223996 bytes) Minimum Memory: DRAM:48 MB Flash:32 MB



This image is only 8MB,why it requires 32MB Flash since basically Flash is used to store IOS image? Is it true that generally I can copy an image to a Flash a little bit larger than the image?As long as I can copy it to flash,I can run it,right?



In flash requirement,I never see sizes like 24MB.Is it because the Flash requirement only has 8,16,32 and so on and those irregular sizes are not considered but I can still run a image smaller than my Flash.For example,run this image with 8MB+4MB SIMM Flash.



Thanks.


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B

Yes.

In my experience if the image will fit the flash it will boot, always.

Some platforms use flash for config storage and there is a small formatting overhead so you need to check the actual free space with sh flash.

8223996 is awfully close to 8M and so it may well not fit into 8M or it might:) Also depends on whether 1M is 1,000 x 1,000 or 1,000 * 1,024 or 1,024 x 1,024:-(

If you want to use the on board web interface thingy then you need more flash. The stated flash requirements for modern routers includes the web thing (ah yes SDM - I finally recalled).

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B

Also worth remembering that you can do a network boot. Not exactly a good idea for production but for a lab it would be worth considering.

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