Re: unable to recover from split-brain in a two-node cluster

Oh, great!

In the meantime, I would _strongly_ recommend you start work on a 
migration plan. There is no danger in the foreseeable future as Linbit 
has no plans to end support, but the stack itself is quite deprecated.

The stack that all major distros have now settled on corosync + 
pacemaker, so this is what I would recommend moving towards. You'll 
probably find that the shift isn't very difficult, as pacemaker was born 
out of the heartbeat project.

Cheers

On 21/06/14 01:47 AM, [email protected] wrote:
> Thanks, Digimer. This is an existing setup so I'm stuck with them. Currently my workaround is to increase the dead time so it won't flap and cause all these issues.
>
> Best,
> -Kaiwei
>
> ----- Original Message -----
> From: "Digimer" <[email protected]>
> To: "General Linux-HA mailing list" <[email protected]>
> Sent: Friday, June 20, 2014 4:19:29 PM
> Subject: Re: [Linux-HA] unable to recover from split-brain in a two-node	cluster
>
> On 20/06/14 03:18 PM, [email protected] wrote:
>> Hi,
>>
>> New to this list and hope I can get some help here.
>>
>> I'm using pacemaker 1.0.10 and heartbeat 3.0.5 for a two-node cluster. I'm having split-brain problem when heartbeat messages sometimes get dropped when system is under high load. However the problem is it never recover back when system load became low.
>>
>> I created a test setup to test this by setting dead time to 6 seconds, and continuously dropping one-way heartbeat packets (udp dst port 694) for 5~8 seconds and resume the traffic for 1~2 seconds using iptables. After the system got into split-brain state, I stop the test and allow all heartbeat traffic to go through. Sometimes the system recovered by sometimes it didn't. There are various symptoms when the system didn't recovered from split-brain:
>>
>> 1. In one instance, cl_status listnodes becomes empty. The syslog keeps showing
>> 2014-06-19T18:59:57+00:00 node-0 heartbeat:  [daemon.warning] [2853]: WARN: Message hist queue is filling up (436 messages in queue)
>> 2014-06-19T18:59:57+00:00 node-0 heartbeat:  [daemon.debug] [2853]: debug: hist->ackseq =12111
>> 2014-06-19T18:59:57+00:00 node-0 heartbeat:  [daemon.debug] [2853]: debug: hist->lowseq =12111, hist->hiseq=12547
>> 2014-06-19T18:59:57+00:00 node-0 heartbeat:  [daemon.debug] [2853]: debug: expecting from node-1
>> 2014-06-19T18:59:57+00:00 node-0 heartbeat:  [daemon.debug] [2853]: debug: it's ackseq=12111
>>
>> 2. In another instance, cl_status nodestatus <node> shows both nodes are active, but "crm_mon -1" shows that each of the two nodes thinks itself is the DC, and peer node is offline. Pengine process is running on one node only. The node not running pengine (but still thinks itself is DC) has log shows crmd terminated pengine because it detected peer is active. After that, the peer status keeps flapping between dead and active, but pengine has never being started again. The last log shows the peer is active (after I stopped the test and allow all traffic). However "crm_mon -1" shows itself is the DC and peer is offline as:
>>
>> [root@node-1 ~]# crm_mon -1
>> ============
>> Last updated: Fri Jun 20 19:12:23 2014
>> Stack: Heartbeat
>> Current DC: node-1 (bf053fc5-5afd-b483-2ad2-3c9fc354f7fa) - partition with quorum
>> Version: 1.0.9-da7075976b5ff0bee71074385f8fd02f296ec8a3
>> 2 Nodes configured, unknown expected votes
>> 1 Resources configured.
>> ============
>>
>> Online: [ node-1 ]
>> OFFLINE: [ node-0 ]
>>
>>    cluster     (heartbeat:ha):      Started node-1
>>
>>
>> Any help, like pointer to the source code where the problem might be, or any existing bug filed for this (I did some search but didn't find matched symptoms) is appreciated.
>>
>> Thanks,
>> -Kaiwei
>
> Hi Kaiwei,
>
>     Is this a new install? If so, that is some very old (and deprecated)
> software. If it is an existing install, then you might find it hard to
> get an answer here (but by all means, you might). Heartbeat hasn't been
> developed in a loooong time, and pacemaker 1.0.x is also very old.
> However, Linbit still offers commercial support for heartbeat. So if you
> don't get help here, you might want to drop them a line.
>
> Cheers, and best of luck.
>


-- 
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without 
access to education?
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