[Gluster-devel] context based defaults for volume options in glusterd

[Krishnan Parthasarathi]

> > Here are a few things that are not clear to me.
> >
> > 1) Does the context-based default value for an option comes into effect
> > only when .value in vme table is NULL?
> If there is context based default then the static default value should
> be NULL is my feeling.
> >
> > 2) IIUC, the generated default value is applied to the volume files
> > generated
> > and persisted no place else. Is this correct?
> Yes.
> >
> > 3) What happens if the context_based_default_get() is not available in all
> > glusterds in the cluster? e.g, upgrade from 3.6 to 3.7.x (where this may
> > land).
> > Shouldn't this behaviour also be 'versioned' to prevent different volume
> > files
> > being served by different nodes of the cluster?
> In the context_based_default_value_get() we can add the version checks
> and generate it the way we want.

Hmm. We have op-version for the options in vme table against which we ensure
that all servers generate the same volume files. What versions would the
context based default value generator functions use? I'd recommend documenting
these details of the proposal and send a PR to gluster-specs repository.
This needs to be reviewed carefully with all the details available in one place.