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

[Jake Smith]

----- Original Message -----
> From: "James Gibbon" <james.gibbon at virgin.net>
> To: "James Gibbon" <james.gibbon at virgin.net>
> Cc: drbd-user at lists.linbit.com
> Sent: Tuesday, July 31, 2012 8:49:52 AM
> Subject: Re: [DRBD-user] DRBD - one half of Proxmox cluster miscommunicating
> 
> 
> Can someone tell me what the "become-primary-on-both" part means? I'm
> fairly anxious to ensure that the second node doesn't attempt to
> become
> primary when its restarted as its data will be out of date..
> 
> 
>         startup {
>                 wfc-timeout  15;
>                 degr-wfc-timeout 60;
>                 become-primary-on both;
>         }
> 
> 
> http://www.pastedump.com/paste/2365

Just what it sounds like - both servers will be allowed to be primary at the same time - "dual primary"

Short version - when secondary comes up it will make sure it is uptodate the it will also be able to become primary at the same time.  However you also have settings that control what happens when the two nodes are not uptodate (these settings are right out of the DRBD users guide for automatic split brain recovery in a dual primary setup - links after):

        net {
                cram-hmac-alg sha1;
                shared-secret "abcxxx";
                allow-two-primaries;
                after-sb-0pri discard-zero-changes;

## sb-1pri says to discard data on the secondary and resync if there has only been the one primary since the last uptodate status
                after-sb-1pri discard-secondary;

## sb-2pri says to disconnect from each other if they have both been primary since the last uptodate - I believe this is where you are at currently.  They have both been primary when they were not connected and uptodate so DRBD is disconnecting them so that you don't overwrite possibly good data.  Manual recovery required
                after-sb-2pri disconnect;
             }

More here:
http://www.drbd.org/users-guide-8.3/s-enable-dual-primary.html
http://www.drbd.org/users-guide-8.3/s-configure-split-brain-behavior.html

HTH

Jake

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