[syslinux] isohybrid and ISO images whose size is not a multiple of 2048 bytes vs. VirtualBox

Thomas Schmitt scdbackup at gmx.net
Fri Feb 20 10:23:31 PST 2015


Rich Mahn:
> The average waste in the second case is just under 12 MiB.  If
> you assume random distribution of ISO sizes, you have to pad by
> 0, 1, 2, or 3 cylinders with equal probability.  That averages
> to 1.5 cylinders, or 12,337,920 bytes, which is just under 12 MiB.

That's because align_factor 1, the current method with
255x63, already produces about 4 MB of average waste.

You are right that the additional average waste by
align_factor 4 in the proposed method is only 12 MB
and additional worst case waste is only 24 MB.

Have a nice day :)


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