[Openstack] howto rescue an instance from a dead host

Thomas Kärgel kaergel at b1-systems.de
Mon Nov 5 09:15:34 UTC 2012


Hi gtt,

Am 05.11.2012 07:53, schrieb gtt116:
> Hi all,
> 
> Any way to rescure an instance when its host is dead.
> Although that teminate and boot a new one is a choice, but is there any
> way to keep the instance's fixed-ips, UUID, floating-ips, etc?

a few days ago i was also confronted with this requirement. Imho there
is only a manual way to do this at the current time.
To "resurrect" a instance on an other host you have to set it to state
"shutdown" in the database, change host value in database, define the
instance in new hypervisor and start it.

Perform the following steps:
-Try to have a look at a database-entries of an instance which you
stopped with "nova stop {instance-name}" and adjust necessary columns in
the entry of the instance to be resurrected. Look for table instances in
nova db. Then set the instance to be resurrected to the same state as
the stopped instance.
-Next change the host value in database of this instance to an available
host.
-Copy over the instance-files to the new host if you are not using
shared storage or whatever...
-Take action to define your instance in hypervisor. How to do this
depends on what type of hypervisor you are using.
-Now you should be able to start your instance on the new host via "nova
start {instance-name}".


kind regards
Thomas



-- 
Thomas Kärgel
Linux Consultant
Tel.: +49-172-2037945
Mail: kaergel at b1-systems.de
B1 Systems GmbH
Osterfeldstraße 7 / 85088 Vohburg / http://www.b1-systems.de
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