[DRBD-user] DRBD - one half of Proxmox cluster miscommunicating

Felix Frank ff at mpexnet.de
Tue Jul 31 17:04:02 CEST 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On 07/31/2012 04:23 PM, James Gibbon wrote:
> Thanks again for your reply, Felix. I'm still a bit confused though,

understandably so I guess ;-)

> I'm sorry to say. In your earlier reply to Jake, you said:
>> > 
>>> > >                 after-sb-1pri discard-secondary;
>> > 
>> > this is an extremely dangerous setting.
>> > 
>> > If for any reason, at the time of reconnection the node with
>> > the stale data is primary, you loose your current data.
>> > 
> My config DOES have this setting. In your earlier comment you say
> that it's not an issue that the secondary box might get promoted
> - but here you say that if it is a primary when it reconnects, the
> current data will be lost..
> Sorry to remain puzzled, appreciate the help;
> James

I stand by this assessment. You got "lucky" insofar that both nodes were
primary when they saw each other again. There is no autorecovery from that.
If for some freak reason your "good" node would have been in a demoted
state at such a time, the stale node would have killed its data.

Please note: If you would have been even more "lucky", your bad node
would have been secondary and your policy would have done the right
thing. The question you have to ask yourself boils down to "how lucky do
you feel in the long run?" ;)

Again: It's paramount to be absolutely sure which dataset is discarded.
The above setting makes the decision a fair bit more arbitrary.


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