[sheepdog-users] Understanding number of copies and offline node behaviour

[Liu Yuan]

On Fri, Sep 06, 2013 at 11:24:23PM +0200, Gerald Richter - ECOS wrote:
> > 
> > I don't think you need to reformat the cluster. 'collie cluster format -c
> > number'
> > this number is the default copy number for a newly created vdi, but you can
> > actually set whatever value you want for each individual vdi.
> > 
> > E.g, you have a cluster formatting with '-c 2' with 4 nodes, then you can
> > 
> > $ collie vdi create new -c 3 # 3 copies for this new or $ collie vdi create new -c
> > 4 # 4 copies for this new.
> > 
> 
> Yes, but only for new vdi's . I have to import about 6 TByte of different vdi's to sheepdog (in a cluster that has for the start two nodes). That frees two additional systems, which I can add to the sheepdog cluster. So I like to bump copies from 2 to 3 and/ or set mode from unsafe to quorum, but as far as I understand the only chance to do so, is to export and reimport the existing vdi's . I can't do this, because I don't have 6TByte additional space...
> 
> How complicated would it be to add the feature to change number of copies and/or mode?

Mode is removed in the recent commit. It is not hard to change copy number on
the fly, maybe 200 lines or more, but need a good understanding of sheepdog code

I think of adding this feature too, but I am busy with other features.

Thanks
Yuan