[Pacemaker] corosync vs. pacemaker 1.1

Kiss Bence bence at noc.elte.hu
Tue Feb 28 01:22:15 EST 2012 

Hi Andrew,

   did You have the time to look at the bug report? Are there anything 
missing from it?

An other question. Maybe it better helps for me to understand the problem.

If a node fails, what is the expected behaviour of the pacemaker to 
recover the node with stonith enabled and without it? What is expected 
from the sysadmin in this procedure?

Bence


On 02/13/2012 02:09 AM, Andrew Beekhof wrote:
> On Sat, Feb 11, 2012 at 2:46 AM, Kiss Bence<bence at noc.elte.hu>  wrote:
>> Hi,
>>
>>
>> On 01/30/2012 04:00 AM, Andrew Beekhof wrote:
>>>
>>> On Thu, Jan 26, 2012 at 2:08 AM, Kiss Bence<bence at noc.elte.hu>    wrote:
>>>>
>>>> Hi,
>>>>
>>>> I am newbie to the clustering and I am trying to build a two node
>>>> active/passive cluster based upon the documentation:
>>>> http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>>>>
>>>> My systems are Fedora 14, uptodate. After forming the cluster as wrote, I
>>>> started to test it. (resources: drbd->    lvm->    fs ->group of services)
>>>> Resources moved around, nodes rebooted and killed (first I tried it in
>>>> virtual environment then also on real machines).
>>>>
>>>> After some events the two nodes ended up in a kind of state of
>>>> split-brain.
>>>> The crm_mon showed me that the other node is offline at both nodes
>>>> although
>>>> the drbd subsystem showed everything in sync and working. The network was
>>>> not the issue (ping, tcp and udp communications were fine). Nothing
>>>> changed
>>>> from the network view.
>>>>
>>>> At first the rejoining took place quiet well, but some more events after
>>>> it
>>>> took longer and after more event it didn't. The network dump showed me
>>>> the
>>>> multicast packets still coming and going. At corosync (crm_node -l) the
>>>> other node didn't appeared both on them. After trying configuring the cib
>>>> logs was full of messages like "<the other node>: not in our membership".
>>>
>>>
>>> That looks like a pacemaker bug.
>>> Can you use crm_report to grab logs from about 30 minutes prior to the
>>> first time you see this log until an hour after please?
>>>
>>> Attach that to a bug in bugs.clusterlabs.org and i'll take a look
>>
>>
>> I had created a bug report: id 5031.
>
> Perfect, I'll look there.
>
>>
>> The "split-brain" is lasting every time about 5 minutes. Meanwhile the two
>> nodes think that the other node is dead. However the drbd is working fine,
>> and properly disallowing the second rebooted node to go Primary. The
>> crm_node -l shows only the local node.
>>
>> Meanwhile one of my question is answered. The multicast issue was a local
>> network issue. The local netadmin fixed it. Now it works.
>>
>> This issue seems to me similar to what James Flatten had reported at 8-th
>> Feb. ([Pacemaker] Question about cluster start-up in a 2 node cluster with a
>> node offline.)
>>
>> The stonith-enabled="false" \
>> and no-quorum-policy="ignore"
>>
>> Thanks in advance,
>> Bence
>>
>>
>>
>>>
>>>>
>>>> I tried to erase the config (crm configure erase, cibadmin -E -f) but it
>>>> worked only locally. I noticed that the pacemaker process didn't started
>>>> up
>>>> normally on the node that was booting after the other. I also tried to
>>>> remove files from /var/lib/pengine/ and /var/lib/hearbeat/crm/ but only
>>>> the
>>>> resources are gone. It didn't help on forming a cluster without
>>>> resources.
>>>> The pacemaker process exited some 20 minutes after it started. Manual
>>>> starting was the same.
>>>>
>>>> After digging into google for answers I found nothing helpful. From
>>>> running
>>>> tips I changed in the /etc/corosync/service.d/pcmk file the version to
>>>> 1.1
>>>> (this is the version of the pacemaker in this distro). I realized that
>>>> the
>>>> cluster processes were startup from corosync itself not by pacemaker.
>>>> Which
>>>> could be omitted. The cluster forming is stable after this change even
>>>> after
>>>> many many events.
>>>>
>>>> Now I reread the document mentioned above, and I wonder why it wrote the
>>>> "Important notice" on page 37. What is wrong theoretically with my
>>>> scenario?
>>>
>>>
>>> Having corosync start the daemons worked well for some but not others,
>>> thus it was unreliable.
>>> The notice points out a major difference between the two operating
>>> modes so that people will not be caught by surprise when pacemaker
>>> does not start.
>>>
>>>> Why does it working? Why didn't work the config suggested by the
>>>> document?
>>>>
>>>> Tests were done firsth on virtual machines of a Fedora 14 (1 CPU core,
>>>> 512Mb
>>>> ram, 10G disk, 1G drbd on logical volume, physical  volume on drbd
>>>> forming
>>>> volgroup named cluster.)/node.
>>>>
>>>> Then on real machines. They have more cpu cores (4), more RAM (4G) and
>>>> more
>>>> disk (mirrored 750G), 180G drbd, and 100M garanteed routed link between
>>>> the
>>>> nodes 5 hops away.
>>>>
>>>> By the way how should one configure the corosync to work on multicast
>>>> routed
>>>> network? I had to create an openvpn tap link between the real nodes for
>>>> working. The original config with public IP-s didn't worked. Is corosync
>>>> equipped to cope with the multicast pim messages? Or it was a firewall
>>>> issue.
>>>>
>>>> Thanks in advance,
>>>> Bence
>>>>
>>>> _______________________________________________
>>>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
>>>> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>>>>
>>>> Project Home: http://www.clusterlabs.org
>>>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>>>> Bugs: http://bugs.clusterlabs.org
>>>
>>>
>>> _______________________________________________
>>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
>>> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>>>
>>> Project Home: http://www.clusterlabs.org
>>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>>> Bugs: http://bugs.clusterlabs.org
>>
>>
>> _______________________________________________
>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
>> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>>
>> Project Home: http://www.clusterlabs.org
>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>> Bugs: http://bugs.clusterlabs.org
>
> _______________________________________________
> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>
> Project Home: http://www.clusterlabs.org
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> Bugs: http://bugs.clusterlabs.org

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