From: realdreams on
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.
From: bod43 on
On 18 May, 07:08, realdreams <legendm...(a)gmail.com> wrote:
> 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?

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).

From: bod43 on

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.