[Gluster-devel] solutions for split brain situation

[Mark Mielke]

On 09/14/2009 07:28 PM, Stephan von Krawczynski wrote:
> I have problems in understanding exactly the heart of your question. Since the
> main reason for rsyncing the data was to take a backup of the primary server,
> so that self heal would have less to do it is obvious (to me) that it has been
> a subvolume of the replicate. In fact is was a backup of the _only_ subvolume
> (remember we configured a replicate with two servers, where one of them was
> actually not there until we offline fed it with the active servers' data and
> then tried to switch it online in glusterfs.
>    

A potentially valid question here - if the backend storage was a 
database as other solutions use, would you expect this to work?

To some degree, rsync from backup is opening up the black box and 
shoving stuff in that you think, in theory, should work.

I don't think this is really the definition of self-heal. I think of 
self-heal is repairing damage. Really, you are sending it all new data 
(extracting from a lossy backup copy) that happens to indirectly inherit 
from previous data, happens to use the same path names, and asking it to 
reconcile the differences. What is being saved here? Even in a self-heal 
situation - it's still going to have to re-write the files, unless it is 
able to detect that some of the leading blocks are in common and only 
send the diffs? The files really are different.

Cheers,
mark

-- 
Mark Mielke<mark at mielke.cc>