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

[Krishnan Parthasarathi]

----- Original Message -----
> 
> 
> On 09/01/2015 12:05 PM, Krishnan Parthasarathi wrote:
> >>> 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.
> The version context based defaults will use is dependent on the version
> the change needs to go into. We will do one thing. We will add this
> proposal to the specs repo and as an example we will give the link to
> the patch for afr quorum which implements this proposal. It will be very
> similar to the current implementation Anuradha came up with absent
> storing on gluster-store from op-version Point of view.
> 

OK