[Linux-HA] Antw: Re: FW: How DC is selected?

[Lars Marowsky-Bree]

On 2012-02-06T09:05:13, Ulrich Windl <Ulrich.Windl at rz.uni-regensburg.de> wrote:

> but like with CPU affinity there should be no needless change of the DC. I also wondered why after each configuration change the DC is newly elected (it seems).

It isn't (or shouldn't be). Still, the DC election is an internal detail
that shouldn't matter to you, unless the re-election is so frequent that
it causes a performance problem ;-)

That also isn't what the original question was about; after split brain
resolution, the "winning" DC is essentially undefined. (It isn't, of
course, but if we explain the algorithm people will come to rely on it
for the wrong reasons.)

But, anyway, the key elements are:

- Oldest version takes precedence;
- Longest uptime;
- Node uuid (essentially random, but a defined internal tie-breaker)

But it really doesn't matter, except in the first case.


Regards,
    Lars

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