[Drbd-dev] drbd.ocf Split-Brain detection patch

[Lars Ellenberg]

On Mon, Nov 15, 2010 at 02:53:04PM +0100, Uwe Grawert wrote:
> Hello,
> 
> the following is a patch for the OCF Agent script, to detect a
> Split-Brain and turn the resource into unmanaged mode if a
> Split-Brain has been detected. This is not meant as a substitution
> for a fencing mechanism but as a help to discover a Split-Brain when
> setting up a cluster.
> 
> 
> --- /usr/lib/ocf/resource.d/linbit/drbd	2010-10-28 14:58:05.000000000 +0200
> +++ drbd.split-brain.patch	2010-11-15 14:28:46.000000000 +0100
> @@ -405,6 +405,9 @@
>  	case "${DRBD_ROLE_LOCAL}" in
>  	Primary)
>  		rc=$OCF_RUNNING_MASTER
> +		# This Node is Primary but StandAlone, there must be a Split-Brain
> +		[[ $OCF_RESKEY_CRM_meta_master_max = 2 && $DRBD_CSTATE = "StandAlone" ]] \
> +		&& rc=$OCF_ERR_CONFIGURED

If only it was so easy.  It it not.
There are other ways to end up in StandAlone.

>  		;;
>  	Secondary)
>  		rc=$OCF_SUCCESS
> @@ -518,6 +521,11 @@
>  		$OCF_RUNNING_MASTER)
>  			ocf_log warn "$DRBD_RESOURCE already Primary, demoting."
>  			do_drbdadm secondary $DRBD_RESOURCE
> +			;;
> +		$OCF_ERR_CONFIGURED)
> +			ocf_log warn "Split-Brain detected! See DRBD logging output."
> +			rc=$status
> +			break
>  		esac
>  		$first_try || sleep 1
>  		first_try=false
> @@ -560,6 +568,11 @@
>  		$OCF_RUNNING_MASTER)
>  			rc=$OCF_SUCCESS
>  			break
> +			;;
> +		$OCF_ERR_CONFIGURED)
> +			ocf_log warn "Split-Brain detected! See DRBD logging output."
> +			rc=$status
> +			break
>  		esac
>  		$first_try || sleep 1
>  		first_try=false
> @@ -591,6 +604,11 @@
>  			;;
>  		$OCF_RUNNING_MASTER)
>  			do_drbdadm secondary $DRBD_RESOURCE
> +			;;
> +			$OCF_ERR_CONFIGURED)
> +			ocf_log warn "Split-Brain detected! See DRBD logging output."
> +			rc=$status
> +			break
>  		esac
>  		$first_try || sleep 1
>  		first_try=false
> @@ -619,6 +637,11 @@
>  		$OCF_RUNNING_MASTER)
>  			ocf_log warn "$DRBD_RESOURCE still Primary, demoting."
>  			do_drbdadm secondary  $DRBD_RESOURCE
> +			;;
> +		$OCF_ERR_CONFIGURED)
> +			ocf_log warn "Split-Brain detected! See DRBD logging output."
> +			rc=$status
> +			break
>  		esac
>  		$first_try || sleep 1
>  		first_try=false

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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