[Pacemaker] DRBD primary/primary + Pacemaker goes into split brain after crm node standby/online

[Lars Ellenberg]

On Mon, Jun 09, 2014 at 08:07:51PM +0200, Alexis de BRUYN wrote:
> Hi Everybody,
> 
> I have an issue with a 2-node Debian Wheezy primary/primary DRBD
> Pacemaker/Corosync configuration.
> 
> After a 'crm node standby' then a 'crm node online', the DRBD volume
> stays in a 'split brain state' (cs:StandAlone ro:Primary/Unknown).
> 
> A soft or hard reboot of one node gets rid of the split brain and/or
> doesn't create one.
> 
> I have followed http://www.drbd.org/users-guide-8.3/ and keep my tests
> as simple as possible (no activity and no filesystem on the DRBD volume).
> 
> I don't see what I am doing wrong. Could anybody help me with this please.

Use fencing, both node-level fencing on the Pacemaker level,
*and* constraint fencing on the DRBD level:

> # cat /etc/drbd.d/sda4.res
> resource sda4 {
>  device /dev/drbd0;
>  disk /dev/sda4;
>  meta-disk internal;
> 
>   startup {
>     become-primary-on both;
>   }
> 
>   handlers {
>     split-brain "/usr/lib/drbd/notify-split-brain.sh root";

 fence-peer crm-fence-peer.sh;
 after-resync-target crm-unfence-peer.sh;

>   }

 	disk {
	 fencing resource-and-stonith;
	 }

> 
>   net {
>     allow-two-primaries;
>     after-sb-0pri discard-zero-changes;
>     after-sb-1pri discard-secondary;
>     after-sb-2pri disconnect;
>   }
>  on testvm1 {
>   address 192.168.1.201:7788;
>  }
>  on testvm2 {
>   address 192.168.1.202:7788;
>  }
> 
>  syncer {
>   rate 100M;
>   al-extents 3389;
>  }
> }
-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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