[ClusterLabs] Clone Issue

Frank D. Engel, Jr. fde101 at fjrhome.net
Sun Feb 14 22:00:07 UTC 2016 

I tried working with a few of these suggestions but the issue doesn't 
seem to be there.  All of them were configured the same way for the 
status page.

After rebooting all of the nodes, two of the ClusterIP resources wound 
up on the same node, and "relocate run ClusterIP-clone" would not 
resolve this.  I ended up taking the node with the duplicate out of the 
cluster (pcs cluster stop) and then adding it back in - this allowed 
that to run, and for some reason, the web site is on all three nodes now.

So far the cluster behavior seems a bit flaky; maybe it is something odd 
in the configuration, but while I can understand how two of the IP 
resources would wind up on the same node initially, I'm not sure why I 
would need to take a node out of the cluster like that to fix it?

In some cases I've needed to reboot the nodes multiple times to get the 
cluster to start behaving again after reboots of nodes for other 
reasons; rebooting one of the three nodes sometimes causes the 
cluster-data-clone (file system) to restart or even just be completely 
lost on all of the nodes, and I've had to reboot a few times to get it 
back.  I could understand that with two nodes down (and it should 
effectively take the filesystem down in that case), but with just one 
going down that seems to be a problem.

Still experimenting and exploring.


Thank you!



On 2/14/2016 10:23, Ken Gaillot wrote:
> On 02/13/2016 08:09 PM, Frank D. Engel, Jr. wrote:
>> Hi,
>>
>> I'm new to the software, and with the list - just started experimenting
>> with trying to get a cluster working using CentOS 7 and the pcs utility,
>> and I've made some progress, but I can't quite figure out why I'm seeing
>> this one behavior - hoping someone can help, might be something simple I
>> haven't picked up on yet.
>>
>> I have three nodes configured (running under VirtualBox) with shared
>> storage using GFS2 - that much seems to be working ok.
>>
>> I have a service called "WebSite" representing the Apache configuration,
>> and I cloned that to create "WebSite-clone", which I would expect to run
>> instances of on all three nodes.
>>
>> However, if I leave "globally-unique" off, it will only run on one node,
>> where if I turn it on, it will run on two, but never on all three.  I've
>> tried a number of things to get this working.  I did verify that I can
>> manually start and stop Apache on all three nodes and it works on any of
>> them that way.
> You don't want globally-unique=true; that's for cases where you want to
> be able to run multiple instances of the service on the same machine if
> necessary, because each clone handles different requests.
>
>> Currently my status looks like this (with globally-unique set to false;
>> "cluster-data" is my GFS2 filesystem):
>>
>> Cluster name: lincl
>> Last updated: Sat Feb 13 20:58:26 2016        Last change: Sat Feb 13
>> 20:45:08 2016 by root via crm_resource on lincl2-hb
>> Stack: corosync
>> Current DC: lincl2-hb (version 1.1.13-10.el7-44eb2dd) - partition with
>> quorum
>> 3 nodes and 13 resources configured
>>
>> Online: [ lincl0-hb lincl1-hb lincl2-hb ]
>>
>> Full list of resources:
>>
>>   kdump    (stonith:fence_kdump):    Started lincl0-hb
>>   Clone Set: dlm-clone [dlm]
>>       Started: [ lincl0-hb lincl1-hb lincl2-hb ]
>>   Master/Slave Set: cluster-data-clone [cluster-data]
>>       Slaves: [ lincl0-hb lincl1-hb lincl2-hb ]
>>   Clone Set: ClusterIP-clone [ClusterIP] (unique)
>>       ClusterIP:0    (ocf::heartbeat:IPaddr2):    Started lincl2-hb
>>       ClusterIP:1    (ocf::heartbeat:IPaddr2):    Started lincl0-hb
>>       ClusterIP:2    (ocf::heartbeat:IPaddr2):    Started lincl1-hb
>>   Clone Set: WebSite-clone [WebSite]
>>       Started: [ lincl0-hb ]
>>       Stopped: [ lincl1-hb lincl2-hb ]
> The above says that the cluster successfully started a WebSite instance
> on lincl0-hb, but it is for some reason prevented from doing so on the
> other two nodes.
>
>> Failed Actions:
>> * WebSite:0_start_0 on lincl2-hb 'unknown error' (1): call=142,
>> status=Timed Out, exitreason='Failed to access httpd status page.',
>>      last-rc-change='Sat Feb 13 19:55:45 2016', queued=0ms, exec=120004ms
> This gives a good bit of info:
>
> * The "start" action on the "WebSite" resource failed no node lincl2-hb.
>
> * The failure was a timeout. The start action did not return in the
> configured (or default) time.
>
> * The reason given by the apache resource agent was "Failed to access
> httpd status page".
>
>> * WebSite:2_start_0 on lincl2-hb 'unknown error' (1): call=130,
>> status=Timed Out, exitreason='none',
>>      last-rc-change='Sat Feb 13 19:33:49 2016', queued=0ms, exec=40003ms
>> * WebSite:1_monitor_60000 on lincl0-hb 'unknown error' (1): call=101,
>> status=complete, exitreason='Failed to access httpd status page.',
>>      last-rc-change='Sat Feb 13 19:53:53 2016', queued=0ms, exec=0ms
>> * WebSite:0_monitor_60000 on lincl0-hb 'not running' (7): call=77,
>> status=complete, exitreason='none',
>>      last-rc-change='Sat Feb 13 19:34:48 2016', queued=0ms, exec=0ms
>> * WebSite:2_start_0 on lincl1-hb 'unknown error' (1): call=41,
>> status=Timed Out, exitreason='none',
>>      last-rc-change='Sat Feb 13 19:53:41 2016', queued=1ms, exec=120004ms
>>
>>
>> PCSD Status:
>>    lincl0-hb: Online
>>    lincl1-hb: Online
>>    lincl2-hb: Online
>>
>> Daemon Status:
>>    corosync: active/enabled
>>    pacemaker: active/enabled
>>    pcsd: active/enabled
>>
>>
>>
>> I'm not sure how to further troubleshoot those "Failed Actions" or how
>> to clear them from the display?
> Pacemaker relies on what the resource agent tells it, so when the
> resource agent fails, you'll have to look at that rather than pacemaker
> itself. Often, agents will print more detailed messages to the system
> log. Otherwise, just verifying the resource configuration and so forth
> is a good idea.
>
> In this case, the big hint is the status page. The apache resource agent
> relies on the /server-status URL to verify that apache is running.
> Double-check that apache's configuration is identical on all nodes,
> particularly the /server-status configuration.
>
> Once you've addressed the root cause of a failed action, you can clear
> it from the display with "pcs resource cleanup" -- see "man pcs" for the
> options it takes.
>
> Another good idea is (with the cluster stopped) to ensure you can start
> apache manually on each node and see the server-status URL from that
> node (using curl or wget or whatever).
>
>> Configuration of the WebSite-clone looks like:
>>
>> [root at lincl2 /]# pcs resource show WebSite-clone
>>   Clone: WebSite-clone
>>    Meta Attrs: globally-unique=false clone-node-max=1 clone-max=3
>> interleave=true
>>    Resource: WebSite (class=ocf provider=heartbeat type=apache)
>>     Attributes: configfile=/etc/httpd/conf/httpd.conf
>> statusurl=http://localhost/server-status
>>     Operations: start interval=0s timeout=120s (WebSite-start-interval-0s)
>>                 stop interval=0s timeout=60s (WebSite-stop-interval-0s)
>>                 monitor interval=1min (WebSite-monitor-interval-1min)
>>
>>
>>
>> Now I change globally-unique to true, and this happens:
>>
>> [root at lincl2 /]# pcs resource update WebSite-clone globally-unique=true
>> [root at lincl2 /]# pcs resource
>>   Clone Set: dlm-clone [dlm]
>>       Started: [ lincl0-hb lincl1-hb lincl2-hb ]
>>   Master/Slave Set: cluster-data-clone [cluster-data]
>>       Slaves: [ lincl0-hb lincl1-hb lincl2-hb ]
>>   Clone Set: ClusterIP-clone [ClusterIP] (unique)
>>       ClusterIP:0    (ocf::heartbeat:IPaddr2):    Started lincl2-hb
>>       ClusterIP:1    (ocf::heartbeat:IPaddr2):    Started lincl0-hb
>>       ClusterIP:2    (ocf::heartbeat:IPaddr2):    Started lincl1-hb
>>   Clone Set: WebSite-clone [WebSite] (unique)
>>       WebSite:0    (ocf::heartbeat:apache):    Started lincl0-hb
>>       WebSite:1    (ocf::heartbeat:apache):    Started lincl1-hb
>>       WebSite:2    (ocf::heartbeat:apache):    Stopped
>>
>>
>> Constraints are set up as follows:
>>
>> [root at lincl2 /]# pcs constraint
>> Location Constraints:
>> Ordering Constraints:
>>    start dlm-clone then start cluster-data-clone (kind:Mandatory)
>>    start ClusterIP-clone then start WebSite-clone (kind:Mandatory)
>>    start cluster-data-clone then start WebSite-clone (kind:Mandatory)
>> Colocation Constraints:
>>    cluster-data-clone with dlm-clone (score:INFINITY)
>>    WebSite-clone with ClusterIP-clone (score:INFINITY)
>>    WebSite-clone with cluster-data-clone (score:INFINITY)
>>
>>
>>
>>
>>
>> As far as I can tell, there is no activity in the Apache log files from
>> pcs trying to start it and it failing or taking too long - it seems that
>> it never gets far enough for Apache itself to be trying to start.
>>
>>
>> Can someone give me ideas on how to further troubleshoot this? Ideally
>> I'd like it running one instance on each available node.
>
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