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

Gerald Richter - ECOS richter at ecos.de
Fri Sep 6 23:24:23 CEST 2013

> 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?

> ....
> To put it simple, data in the sheepdog cluster are auto-healing. With more
> nodes added in, you just aggregate more space and power linearly into the
> cluster.

Thanks for your detailed explanation, that really sound very good.



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