- Use dwarfs instead SquashFS https://github.com/mhx/dwarfs
- Add lz4 and zstd and use this compression by default
while this seems interesting for using compressed read-only archives of data, there is no native driver for it in the kernel, you wont be able to boot from such an image easily (while you can use fuse it will eat all the performance gains dwarfs brings you) and this is an essential feature for Ubuntu Core (it boots the base snap as root filesystem) … i also doubt using a userspace filesystem like fuse will be considered particulary safe by our security team (ICBW indeed) vs something that is a signed kernel module like squashfs.ko
snapd supports plenty of distros, some of these (i.e. CentOS/RedHat) have kernels that do/will not support zstd so there is no way to make this a default … have a look at:
and
for more details
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Thanks for reply.
As for the second point of my post, I would like to say that it is probably better to also propose another compression algorithm and remove the xz algorithm, which, as I understand it, still works
xz will stay around as an option because size matters in the IoT world 
but LZO has been made the default a while ago in new snapcraft projects … there are discussions within the snapd team about other compression options as i understand …
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Sorry for the necroposting, but I heard that Canonical is preparing a full-fledged snap-desktop, so I have a question (very old actually) if you can use snap mounting not at system startup, but one-click, if I understand correctly, that’s how dmg works in macOS. Also, isn’t it time to add zstd as an alternative, like for browsers or jetbrains products?