[Linux-cluster] virtualized guest failback

[Stepan Kadlec]

John Ruemker wrote:
> Stepan Kadlec wrote:
>> Hi,
>> I have working failover of virtualized guest. could someone give me 
>> hint how to configure the vm failover to failback after recovery? eg. 
>> vm_A runs xen01, xen01 fails, so xen02 takes over the vm_A, after 
>> xen01 is up again, the vm_A is migrated back to xen01.
>>
>> I have already tried many config combinations, but without success - 
>> the vm_A always stays on the failover host.
>>
>> my expected config (which still doesn't work) is:
>>
>>  <rm>
>>     <failoverdomains>
>>       <failoverdomain name="xen01" restricted="1" ordered="1">
>>         <failoverdomainnode name="xen01.localdom" priority="2"/>
>>         <failoverdomainnode name="xen02.localdom" priority="1"/>
>>       </failoverdomain>
>>       <failoverdomain name="xen02" restricted="1" ordered="1">
>>         <failoverdomainnode name="xen01.localdom" priority="1"/>
>>         <failoverdomainnode name="xen02.localdom" priority="2"/>
>>       </failoverdomain>
>>     </failoverdomains>
>>     <resources/>
>>
>>     <vm autostart="1" domain="xen01" exclusive="0" migrate="live" 
>> name="vm_A" path="/etc/xen/vm" recovery="relocate"/>
>>     <vm autostart="1" domain="xen02" exclusive="0" migrate="live" 
>> name="vm_B" path="/etc/xen/vm" recovery="relocate"/>
>>   </rm>
>>
>> any hints? thanks stepan
> 
> 
> Your failoverdomains are setup to allow that, but it looks like you have 
> your priorities switched.  Domain xen01 prefers xen02.localdom and 
> domain xen02 prefers xen01.localdom, since the lowest priority score in 
> a domain is preferred.  So since vm_A is in xen01 it will choose to 
> start the guest on xen02.localdom.  If that node fails it will move to 
> xen01.localdom, and will fail back to xen02.localdom if that node 
> returns.  Switch the priorities in each domain and you should have the 
> behavior you want
> 
> 
>      <failoverdomain name="xen01" restricted="1" ordered="1">
>        <failoverdomainnode name="xen01.localdom" priority="1"/>
>        <failoverdomainnode name="xen02.localdom" priority="2"/>
>      </failoverdomain>
>      <failoverdomain name="xen02" restricted="1" ordered="1">
>        <failoverdomainnode name="xen01.localdom" priority="2"/>
>        <failoverdomainnode name="xen02.localdom" priority="1"/>
>      </failoverdomain>
> 
> 
> -John
> 

unfortunately, even if the priorities are inversed, the failback doesn't 
work - the service taken over while the default node is down is never 
moved back after the node is recovered :-(.

current setup:

  <failoverdomains>
    <failoverdomain name="xen01" restricted="1" ordered="1">
      <failoverdomainnode name="xen01.localdom" priority="1"/>
      <failoverdomainnode name="xen02.localdom" priority="2"/>
    </failoverdomain>
    <failoverdomain name="xen02" restricted="1" ordered="1">
      <failoverdomainnode name="xen01.localdom" priority="2"/>
      <failoverdomainnode name="xen02.localdom" priority="1"/>
    </failoverdomain>
  </failoverdomains>

  <vm autostart="1" domain="xen01" exclusive="0" migrate="live" 
name="vm_A" path="/etc/xen/vm" recovery="relocate"/>
  <vm autostart="1" domain="xen01" exclusive="0" migrate="live" 
name="vm_B" path="/etc/xen/vm" recovery="relocate"/>

  <vm autostart="0" domain="xen02" exclusive="0" migrate="live" 
name="vm_C" path="/etc/xen/vm" recovery="relocate"/>

so vm_A and vm_B should be running preferably on xen01 and vm_C on 
xen02, but if I reboot xen01, both vm_A and vm_B are started 
(failovered) on xen02 but remain there even if xen01 comes up again.

what can be wrong?

sincerely steve