[DRBD-user] Consistent device to primary fences remote node

Lars Ellenberg lars.ellenberg at linbit.com
Wed Nov 26 17:40:38 CET 2008

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

On Wed, Nov 26, 2008 at 11:15:00AM +0100, Federico Simoncelli wrote:
> Hi all. I noticed that promoting to primary a "ds:Consistent/DUnknown"
> device automatically triggers a "/sbin/drbdadm outdate-peer".
> 1) During normal operation the status is:
> 0: cs:Connected st:Primary/Primary ds:UpToDate/UpToDate C r---
> 2) Unplugging the cable the node 1 fences the node 2 and its status becomes:
> 0: cs:WFConnection st:Primary/Unknown ds:UpToDate/Outdated C r---
> 3) Booting the node 2 (keeping the cable disconnected) and running
> "drbdadm adjust all" (for debug purpose) I can see that on this side
> the status is:
> 0: cs:WFConnection st:Secondary/Unknown ds:Consistent/DUnknown C r---
> 4) Running the command "drbdadm sh-b-pri all" on node 2 (as the drbd
> init script would do after adjust and wait-connect) the "/sbin/drbdadm
> outdate-peer" is triggered.
> The problem here is that the node 1 (the one holding the updated data)
> get fenced without reason and it also risks to become later a
> SyncTarget losing the updated data.
> I suppose that the problem is my outdate-peer which just fences the
> node without actually outdate it.
> Even if this is the reason I think that a "Consistent" device should
> not be allowed to become primary (fencing the remote node) without any
> confirmation.

the "confirmation" is supposed to come from the outdate-peer handler.
a current Primary will refuse to be Outdated,
the outdate would fail,
denying the promotion of the merely Consistent one.

> What do you think about this? Am I missing something?
> My current configuration:
> become-primary-on both;
> allow-two-primaries;
> after-sb-0pri discard-zero-changes;
> after-sb-1pri discard-secondary;
> after-sb-2pri disconnect;
> fencing resource-and-stonith;
> outdate-peer "/usr/lib/drbd/obliterate-peer.sh";
> The "/usr/lib/drbd/obliterate-peer.sh" script is available at:
> http://people.redhat.com/lhh/obliterate
> (It basically fences the other node using "fence_node" and it returns
> the exit code 7 on success)
> -- 
> Federico.
> _______________________________________________
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> drbd-user at lists.linbit.com
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: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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