Changing XEN VM configuration
What is the correct way to update a XEN VM configuration?
In this case I want a specific domain to stop using /dev/emcpowerg and use /dev/emcpowerh in stead.
I have ensured that the two devices have identical geometry and have copied the contents from the one to the other (using dd)
Then I found two config files in /etc/xen/vm which refer /dev/emcpowerg and I replaced the g with an h in both places.
However when I run xm list --long domain_name|grep emc I still get the emcpowerg device name... So either there is another place where the config is stored .... or maybe some daemon has got a resident configuration kept in memory?
How do I correctly remove dependency on the old LUN/block device (the storage array is due to be decommissioned)
P.S. Note that the domain has been down for the entire operation.
Solution 1:
Ok this solves the riddle.
If xm list shows your DomU without ID this is a so-called "managed DomU".
In this case the configuration is permanently loaded into the xen-store.
To reload its configuration you need to issue xm delete for the DomU.
After that use xm new to recreate it with the new settings (without starting it up).
Solution 2:
I found the correct solution - my initial surmise was correct - Xen does indeed store the VM configurations somewhere other than in /etc/xen/vm
The daemon Xend manages the configuration and editing the files located under /etc/xen/vm is not recommended as they are only used to create new VMs.
The process to change a VM configuration is
Shut down the VM (DomU)
-
Export the VM configuration to a text file with the command
xm list -l DomU_name > vm.conf Use a text editor to edit file VM configuration, eg
vi vm.conf-
Delete the VM from Xend and re-create it using the modified config file, using the following commands:
xm del DomU_namexm new -F vm.conf -
Start the modified VM
xm start DomU_name
This website, in particular this page, proved very useful: http://doc.opensuse.org/products/draft/SLES/SLES-xen_sd_draft/cha.xen.manage.html