root on zfs overlayfs issue with docker (RENAME_WHITEOUT)


Active Member
Oct 28, 2019
Austin, TX

I have some LXC containers with docker running inside them. Those work well with root-on-ext4, with the required changes in the .conf files.

When I do the same on root-on-zfs, I get the following messages in the console:

overlayfs: upper fs does not support RENAME_WHITEOUT.
overlayfs: upper fs is missing required features.

Are these harmless? Those containers work as expected, but will this cause an issue later on?

Thank you!
First: Docker is best used inside of VMs. This was true and still is true.
Running Docker inside of LX(C) containers is still not on par with "native" emulation and can still break sometimes - at least it did in the past. Docker is officially not supported in LX(C) containers in PVE, therefore it may or may not work as expected. Running with any type of additional virtualization of a filesystem (aufs, overlayfs, ...) on top of ZFS can work but is certainly not fast. So to answer your question, your guess is as good as mine.

I also see some hickups with Docker and containers and it is not running as smoothly as it would be in a "real" VM.
I still hope to see ZFS support inside LX(C) containers, so that you can directly use ZFS with Docker, which is superior to any other form when already run on ZFS. This would be a huge speed improvement and any additional filesystem virtualization layer is then unnecessary.
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I see the same with Proxmox 7.1-8 and Docker in unprivileged LXCs. I did not notice any issues or performance Problems, usually this is only reported once, when the LXC/Docker starts. All my containers still work.

I have /var/lib/docker mounted from a ZVOL (ZFS) that is formatted as XFS.
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