Re: Synchronization levels in SR

On Wed, 2010-05-26 at 17:31 -0400, Jan Wieck wrote:

> You can do this only with per standby options, by giving each standby a 
> weight, or a number of votes. Your DEV server would have a weight of 
> zero, while your production standby's have higher weights, depending on 
> their importance for your overall infrastructure. As long as majority 
> means >50% of all votes in the house, you don't have a split brain risk.

Yes, you could do that with per-standby options.

If you give each standby a weight then the parameter has much less
meaning for the user. It doesn't mean number of replicas any more, it
means something else with local and changeable meaning. A fractional
quorum suffers the same way.

What would make some sense would be to have an option for "vote=0|1" so
that a standby would never take part in the transaction sync when
vote=0.

But you still have the problem of specifying rules if insufficient
servers with vote=1 are available. The reaction to that is to supply
more servers with vote=1, though then you need a way to specify how many
servers with vote=1 you care about.

-- Simon Riggs           www.2ndQuadrant.com