[arch-releng] reduce image size

[Gerardo Exequiel Pozzi]

On 10/02/2015 06:02 AM, Christian Hesse wrote:
> Christian Hesse <list at eworm.de> on Thu, 2015/10/01 16:53:
>> Hello everybody,
>>
>> now that we support root filesystem on squashfs/overlayfs... Do we want to
>> reduce image size some more?
>>
>> Currently we generate a squashfs for each architecture, one for x86_64 and
>> one for i686. How about merging these into one filesystem? Only extra thing
>> to do is a bind mount for the subdirectory to /new_root.
> 
> That's not true... We do not have to bind mount but add the arch to
> path overlay mount options.
> 
>> The benefit is the deduplication support in squashfs, identical files are
>> added to the filesystem just once. I did not yet test with the official
>> media, but I'd expect the size to shrink about 120MB...
> 
> I've build my own media and reduced size from 892M to 738M.
> 
>> This has a drawback, though: Copy-to-RAM would copy the files for both
>> architectures, not just the needed one.
> 
> To compare... To split airootfs.sfs image were about 400MB each... The single
> one with both archs is 641MB.
> 
>> Any comments?
> 
> Did some quick and dirty hacks:
> 
> https://github.com/eworm-de/archiso/commits/single-squashfs
> 
> This needs some polishing... Would be great to have a single switch to decide
> whether or not the build a single airootfs.
> 
> Comments are still welcome. ;)
> 

This is really great, the only downside is I am not sure how good for
"releng" iso: for example for PXE setups, more bw needed+more memory,
more memory needed on copytoram, and on loopback boot.

I agree in adding as optional feature, but not by default for "releng".

Thanks for your work!


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