multiboot btrfs subvolumes

this idea has been knocking around in my head for a while. i want to document it, while it is still there and to flush it out later..

i usually multiboot, and have several operating systems on the same disk. my currently laptop has about dozen+ partitions. each os is fully contained within a partition, including the bootloader on pbr. mbr is clean. partitions are efficient in one way by segregating diskspace, but scatter diskspace utilisation inefficiently.

about half of those dozen+ partitions have btrfs. and i haven't had any btrfs trouble, apart from newer versions not being backward compatible. for eg, wheezy can't access the stretch partition, due to some new btrfs features. but bleeding-edge stretch, ubuntu, and arch can access each other's btrfs partitions.

gentoo docs gave me this idea, but it was ubuntu which made it practical. the default ubuntu install created two subvolumes, one for root and another for home. what-if i create yet more subvolumes and install another os in each subvolume? could they coexist together on the same btrfs partition, albeit different subvolumes? and still keep themselves separate? i think so.

one major risk would be an install wanting to format the partition. that might wipe all subvolumes in that partition.

i could mitigate that risk by keeping a separate btrfs partition just for installing, and post-install copy to a relevant new subvolume in my main btrfs partition.

i would have to keep a separate btrfs partition for each os which doesn't have the bleeding-edge btrfs. all the ones on bleeding-edge could be lumped in the same partition on different subvolumes.

i did a quick search to check whether someone else might have tapped this/similar idea from the collective consciousness ;)
yes they have :) and i can learn from their experience..


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