Comment 5 for bug 1632085

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Steve Langasek (vorlon) wrote :

From the mailing list:

I don't think a 'fudge factor' option is particularly clean or intuitive. I
think what you actually want is to be able to declare the overall size of
the image that you're building. It's a waste of mental energy to think
about VM image sizes in increments less than 1G, especially given that these
are all still going to be sparse files.

So I would suggest:

 - a --size option to ubuntu-image to specify the full image size (needs
   some careful thought for the multiple-image case)
 - keep the 50% buffer on ext4 filesystem size as a floor (the '50%' can be
   refined over time with investigation into the actual size requirements
   for ext4 metadata, but this is not a high priority; highest priority is
   that it works reliably)
 - if --size is smaller than the minimum size needed to accommodate the
   contents, warn but build the image anyway - because all the expensive
   work of ubuntu-image happens /before/ we're able to calculate the final
   size, so throwing that all away at the end would be /very annoying/.