In case this was not clear: my Ansible demo exactly follows what Brian recommends here. It creates all the required directories for each instance and configures each instance to use those. The configuration folder is shared, but each instance as it owns standalone.xml (which means that all instances share the same management users list). 

@Tomas Hofman sorry, I misunderstood your question: I thought you were asking HOW to have several instances running on one host, not if it was possible for them to share the same folders. My bad, I could have tell you already that it was indeed not supported.

On Wed, Mar 2, 2022 at 9:44 AM Tomas Hofman <thofman@redhat.com> wrote:
Thanks Brian,

this is the statement I wanted to get :).

Tomas

On 3/2/22 04:11, Brian Stansberry wrote:
> The design of the software is to not share the subdirectories under
> standalone. This is noted under
> https://docs.wildfly.org/26/Getting_Started_Guide.html#wildfly-directory-structure
> <https://docs.wildfly.org/26/Getting_Started_Guide.html#wildfly-directory-structure>.
>
> It's possible to get away with sharing the configuration dir but I
> wouldn't recommend doing so unless you are very clear on your use case,
> as the server writes there during boot, and of course if you use a
> management agent to modify the config.  Note that if you use the
> deployment-scanner you are using a management agent to modify the
> config, as the scanner is just a built in automated management agent.
>
> Also, sharing standalone/deployments will break things as the scanner
> writes there and assumes that any changes there were either made by it
> or by a user telling it what to do.
>
>
> On Wed, Feb 16, 2022 at 2:55 AM Romain Pelisse <belaran@redhat.com
> <mailto:belaran@redhat.com>> wrote:
>
>     Hi Tomas,
>
>     Running multiple instances of EAP on one host is fairly easy, but
>     does requires to get all the details right.I made an Ansible demo to
>     showcase this exact use case
>     <https://github.com/ansible-middleware/wildfly-cluster-demo>. You
>     may even be able to reuse the automation.
>
>     In short, in this demo, I keep the standalone.xml in the
>     standalone/configuration folder, but data, tmp and log are instance
>     specific and located elsewhere.
>
>     On Wed, Feb 16, 2022 at 9:43 AM Tomas Hofman <thofman@redhat.com
>     <mailto:thofman@redhat.com>> wrote:
>
>         Hello,
>
>         could anybody confirm if it's OK (or not OK) to run multiple
>         clustering
>         Wildfly instances that would share common standalone/ directory?
>         Even if
>         the instances are supposed to be running the same deployments?
>
>
>         I always thought that the standalone/ directory should be
>         separate for
>         each Wildfly/EAP instance, but I can't find any resources that
>         would
>         clearly state that shared standalone/ is a problem.
>
>         The problems I think of are:
>
>         * instances could override their standalone.xml config,
>         * instances could override some transactional or cache data?
>
>         Thanks :),
>         Tomas
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> Brian Stansberry
> Principal Architect, Red Hat JBoss EAP
> He/Him/His