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    A shame to build this kind of thing with LVM2. ZFS could have been designed for this use case: It can create a block device, snapshot it, create clones (in constant time), modify them by applying more layers, and store only the deltas.

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      The licensing issues around ZFS make it a non-starter for a lot of places.

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        There are no licensing issues around ZFS, there are licensing issues round ZFS on Linux. That sounds like a reason to build your infrastructure on FreeBSD, rather than a reason to use LVM2.

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          As I understand it, fly.io uses a lot of Linux-specific technologies - Amazon’s Firecracker, Wireguard, eBPF, etc. It’s not impossible to build something that runs Docker containers based on FreeBSD, but switching fly.io to FreeBSD would not be a trivial undertaking.

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            If I understood the blog post correctly, they’re running the containers in a separate VM. There’s no reason why that VM couldn’t be Linux even if the VM that’s exporting the block devices is FreeBSD.

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            What’s the freebsd container ecosystem look like? Vanishingly small compared to what is available for Linux. Picking freebsd to get zfs in a container runtime system is the tail wagging the dog. As nice as zfs is you can still build cool stuff with LVM2/DM.

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            Honest question about dishonesty: if a company never advertises they use ZFS, how can licensing issues affect them? How would anyone detect they used ZFS?

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              The licensing issues only apply to open-source distribution. A company can use whatever they want as long as they don’t distribute the software under a license that clashes with that of ZFS.

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                Disgruntled staff leaking info? Server logs from package downloads? Discovery in an unrelated lawsuit?

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            Anyone used fly? It looks interesting but I’d appreciate any first-hand experience from crustaceans

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              I do. It works very well for some applications, and the team is extremely responsive when someone runs into the occasional glitch.

              A cursory look at https://community.fly.io should give you a good intuition on what works well on Fly and what needs a little bit of love.