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Created attachment 437572[details]
vdsm logs
Description of problem:
vm 'split brain' scenario is created in case vdsm loses its connection to libvirt somehow (*) on destination machine, and migration from source (valid source) to that destination takes place.
migration is reported as 'failed', and 'qemu' process is so called dies, however, migration succeeds to destination on virsh, this results a state, where vdsm 'thinks' vm is down (and rhevm respectively), and will try to run this vm on different host, which will result 'split brain'.
(*) how ?
1) make sure you have 2 hosts ('host-a' and 'host-b')
2) make sure you have connected storage (i use iscsi)
3) run the following commands on 'host-b'
- kill -STOP `pgrep libvirt`
- service libvirtd restart
4) create a new domain (machine) on 'host-a' and make sure it runs
5) migrate this vm from 'host-a' to 'host-b'
result:
migration will fail on source, however, it will succeeds on libvirt.
This happens because we may miss the libvirt event (domain finished migration) when we were down. This should be solved by checking on recovery if we are migration destination then recheck VM status and if it's running change our VM status accordingly..
Using steps described in Description with vdsm-4.9-70.el6.x86_64, during migration the machine status in RHEV-M was down. After but according backend log, migration was in progress:
2011-05-31 16:58:22,131 INFO [com.redhat.rhevm.vdsbroker.VdsUpdateRunTimeInfo] (QuartzScheduler_Worker-12) vds::refreshVmList vm id 4f65e6ab-3bd1-4a69-be84-326ee9d988a8 is migrating to vds srh-11 ignoring it in the refresh till migration is done
Migration failed in RHEV-M at 17:02 according events. No ERROR in backend nor vdsm logs. Backend, source vds's and targer vds's vdsm and libvirt logs are attached in next comment.
In libvirt is error
16:57:46.712: 12070: error : remoteIO:10569 : Domain not found: no domain with matching uuid '4f65e6ab-3bd1-4a69-be84-326ee9d988a8'
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
http://rhn.redhat.com/errata/RHEA-2011-1782.html
Created attachment 437572 [details] vdsm logs Description of problem: vm 'split brain' scenario is created in case vdsm loses its connection to libvirt somehow (*) on destination machine, and migration from source (valid source) to that destination takes place. migration is reported as 'failed', and 'qemu' process is so called dies, however, migration succeeds to destination on virsh, this results a state, where vdsm 'thinks' vm is down (and rhevm respectively), and will try to run this vm on different host, which will result 'split brain'. (*) how ? 1) make sure you have 2 hosts ('host-a' and 'host-b') 2) make sure you have connected storage (i use iscsi) 3) run the following commands on 'host-b' - kill -STOP `pgrep libvirt` - service libvirtd restart 4) create a new domain (machine) on 'host-a' and make sure it runs 5) migrate this vm from 'host-a' to 'host-b' result: migration will fail on source, however, it will succeeds on libvirt.