ZFS Support in CoreOS

[Nick]

Hopefully this is the right place to ask...

• Are there any plans to include ZFS support out-of-the-box?
  
• Are there any official or recommended guides on setting up ZFS on CoreOS?
  

I have a ZFS data pool from the previous Ubuntu 14.04 LTS server, that'd I'd like to utilise in CoreOS (I don't have the spare storage, to change the underlying file system!).

There are plenty of tutorials, but most of them come with the disclaimer "don't use in production" (which scares me, quite frankly).

• https://github.com/varasys/corezfs
• https://github.com/ClusterHQ/flocker/blob/zfs-on-coreos-tutorial-667/docs/experimental/zfs-on-coreos.rst
  
• https://lorenz.brun.one/setting-up-zfs/
• https://groups.google.com/forum/#!searchin/coreos-dev/zfs|sort:date/coreos-dev/mNWC0kW9kdk/y4MLKm2VBwAJ
  

I'd just like to know what the "official word" is, and whether I should start looking at alternatives. 

Thanks,

Nick

(Alternatives -> Could a Ubuntu 18.04 LTS docker container access the /dev/sdx ZFS devices? Or is that too far fetched?)

[David Michael]

On Thu, Apr 12, 2018 at 10:28 AM, Nick <nickg...@gmail.com> wrote:
> Hopefully this is the right place to ask...
>
> Are there any plans to include ZFS support out-of-the-box?

No drivers will be included that aren't part of the mainline kernel.

> Are there any official or recommended guides on setting up ZFS on CoreOS?

No, but maybe this project would help:
https://github.com/lorenz/torcx-zfs . That uses torcx to package
everything, so it uses the same mechanism as Docker to enable the
optional software.

> (Alternatives -> Could a Ubuntu 18.04 LTS docker container access the
> /dev/sdx ZFS devices? Or is that too far fetched?)

You would still need to compile the drivers for the CoreOS kernel.

Thanks.

David

[Nick]

Hi David,

Thanks for the reply, torcx-zfs looks good. But I'm a bit out of my depth here, and the instructions are a bit brief for me to fill in the gaps. (e.g. is `coreos-devel` a fork of a git repo? Which folder would I "copy the repository into"?)

• Is there any documentation I should be reading to help get me started? (e.g. https://coreos.com/os/docs/latest/sdk-modifying-coreos.html ?)
  
• Is it worth contacting @lorenz to ask for "spoon fed" instructions?
  
• Will this torcx feature help simplify the process (on track for 23rd May 2018)? https://github.com/coreos/bugs/issues/2215
  

Thanks,

Nick

[David Michael]

On Fri, Apr 13, 2018 at 10:41 AM, Nick <nickg...@gmail.com> wrote:
> Hi David,
>
> Thanks for the reply, torcx-zfs looks good. But I'm a bit out of my depth
> here, and the instructions are a bit brief for me to fill in the gaps. (e.g.
> is `coreos-devel` a fork of a git repo? Which folder would I "copy the
> repository into"?)

It looks like the coreos-devel stuff is just set up so you can use
Docker. You shouldn't need that if you use nspawn to start the
container. It meant to copy the repo into the container.

> Is there any documentation I should be reading to help get me started? (e.g.
> https://coreos.com/os/docs/latest/sdk-modifying-coreos.html ?)

Maybe https://coreos.com/os/docs/latest/kernel-modules.html will be
more useful in this case. The SDK is normally for building an entire
new OS image.

> Is it worth contacting @lorenz to ask for "spoon fed" instructions?

Yes, that project is not developed by CoreOS, so contacting him
directly will be the best way to get details.

> Will this torcx feature help simplify the process (on track for 23rd May
> 2018)? https://github.com/coreos/bugs/issues/2215

It could simplify selecting your ZFS torcx image, but I don't think
that change was concerned with building images.

If torcx is more than you want to deal with for this, I wrote a
separate script for building kernel modules and used ZFS as an example
at https://gist.github.com/dm0-/0db058ba3a85d55aca99c93a642b8a20 .
That example doesn't install the userspace components, but I think one
of the forks expanded it to do so.

Thanks.

David