Editing libvirt xml file
Hi,
I edited the libvirt xml (virsh edit...) file of a running Windows server instance because I changed the video model type from cirrus to vmvga so it can support a higher resolution on a console (cirrus supports up to 1280 only). After editing, i "soft-rebooted" the instance and the new configuration sticks. That's awesome.
But when you do a "hard-reboot" it will revert back to the original config. I also tried to do a "shut-down" then "start" again, but it still reads the original config. Not sure where it is reading the config from...
Regards Vlad
On Fri, 2020-10-30 at 11:56 -0500, vladimir franciz blando wrote:
Hi, I edited the libvirt xml (virsh edit...) file of a running Windows server instance because I changed the video model type from cirrus to vmvga so it can support a higher resolution on a console (cirrus supports up to 1280 only). After editing, i "soft-rebooted" the instance and the new configuration sticks. That's awesome.
Please don't do this :) You shouldn't change things about an instance behind nova's back. It breaks resource tracking and can cause all sorts of horribleness.
But when you do a "hard-reboot" it will revert back to the original config.
Hard reboot builds configuration from scratch, dumping the existing XML. This is built from the same things used when you first create the instance (flavor + extra specs, image + metadata, host-level config, ...).
What you want is the 'hw_video_model' image metadata property. Set this and rebuild your instance:
openstack image set --property hw_video_model=vmvga $IMAGE openstack server rebuild $SERVER $IMAGE
Note that rebuild is a destructive operation so be sure you're aware of what this is doing before you do it.
Stephen
I also tried to do a "shut-down" then "start" again, but it still reads the original config. Not sure where it is reading the config from...
Regards Vlad
On Fri, 2020-10-30 at 17:23 +0000, Stephen Finucane wrote:
On Fri, 2020-10-30 at 11:56 -0500, vladimir franciz blando wrote:
Hi, I edited the libvirt xml (virsh edit...) file of a running Windows server instance because I changed the video model type from cirrus to vmvga so it can support a higher resolution on a console (cirrus supports up to 1280 only). After editing, i "soft-rebooted" the instance and the new configuration sticks. That's awesome.
Please don't do this :) You shouldn't change things about an instance behind nova's back. It breaks resource tracking and can cause all sorts of horribleness.
if you have support form an openstack vendor like redhat editing the domain xml also make that vm unsupported until its restroed to the way nova generated. it might also make other issue caused as a resulted unsupported. so unless you are self supporting you cloud be very carful with doing this.
But when you do a "hard-reboot" it will revert back to the original config.
Hard reboot builds configuration from scratch, dumping the existing XML. This is built from the same things used when you first create the instance (flavor + extra specs, image + metadata, host-level config, ...).
What you want is the 'hw_video_model' image metadata property. Set this and rebuild your instance:
openstack image set --property hw_video_model=vmvga $IMAGE
this is the supported way to change this value ^ it will take effect for new instances.
openstack server rebuild $SERVER $IMAGE
and this is the only supported api action that can also change this value. however i dont think rebuilding to the same image will update the image metadata. you currenlty need to rebuild to a new image. this is due to an optiomisation we have to avoid needing to go to the scheuler if we use the same image.
the unsupported way to change this without rebuilding the instance is to add img_hw_video_model=vmvga to the system metadata table for that instance.
if your cloud is supported by a vendor this will also invalidate your suport in all likely hood as db modificaiton generally are unsupported without an exception. if you can rebuild the guest that is the best approch but it wont work for boot form volume instances and it willl destory all data in the root disk of all other instances.
Note that rebuild is a destructive operation so be sure you're aware of what this is doing before you do it.
Stephen
I also tried to do a "shut-down" then "start" again, but it still reads the original config. Not sure where it is reading the config from...
Regards Vlad
Yes, I am fully aware of support implications if you edit this. But fortunately this is not in any way a vendor support OpenStack deployment
On Fri, Oct 30, 2020 at 1:29 PM Sean Mooney smooney@redhat.com wrote:
On Fri, 2020-10-30 at 17:23 +0000, Stephen Finucane wrote:
On Fri, 2020-10-30 at 11:56 -0500, vladimir franciz blando wrote:
Hi, I edited the libvirt xml (virsh edit...) file of a running Windows server instance because I changed the video model type from cirrus to vmvga so it can support a higher resolution on a console (cirrus supports up to 1280 only). After editing, i "soft-rebooted" the instance and the new configuration sticks. That's awesome.
Please don't do this :) You shouldn't change things about an instance behind nova's back. It breaks resource tracking and can cause all sorts of horribleness.
if you have support form an openstack vendor like redhat editing the domain xml also make that vm unsupported until its restroed to the way nova generated. it might also make other issue caused as a resulted unsupported. so unless you are self supporting you cloud be very carful with doing this.
But when you do a "hard-reboot" it will revert back to the original config.
Hard reboot builds configuration from scratch, dumping the existing XML. This is built from the same things used when you first create the instance (flavor + extra specs, image + metadata, host-level config, ...).
What you want is the 'hw_video_model' image metadata property. Set this and rebuild your instance:
openstack image set --property hw_video_model=vmvga $IMAGEthis is the supported way to change this value ^ it will take effect for new instances.
openstack server rebuild $SERVER $IMAGEand this is the only supported api action that can also change this value. however i dont think rebuilding to the same image will update the image metadata. you currenlty need to rebuild to a new image. this is due to an optiomisation we have to avoid needing to go to the scheuler if we use the same image.
the unsupported way to change this without rebuilding the instance is to add img_hw_video_model=vmvga to the system metadata table for that instance.
if your cloud is supported by a vendor this will also invalidate your suport in all likely hood as db modificaiton generally are unsupported without an exception. if you can rebuild the guest that is the best approch but it wont work for boot form volume instances and it willl destory all data in the root disk of all other instances.
Note that rebuild is a destructive operation so be sure you're aware of what this is doing before you do it.
Stephen
I also tried to do a "shut-down" then "start" again, but it still reads the original config. Not sure where it is reading the config from...
Regards Vlad
Already found a solution which entails hacking nova database, specifically the instance_system_metadata table
Regards Vlad
On Fri, Oct 30, 2020 at 4:57 PM vladimir franciz blando < vladimir.blando@gmail.com> wrote:
Yes, I am fully aware of support implications if you edit this. But fortunately this is not in any way a vendor support OpenStack deployment
On Fri, Oct 30, 2020 at 1:29 PM Sean Mooney smooney@redhat.com wrote:
On Fri, 2020-10-30 at 17:23 +0000, Stephen Finucane wrote:
On Fri, 2020-10-30 at 11:56 -0500, vladimir franciz blando wrote:
Hi, I edited the libvirt xml (virsh edit...) file of a running Windows server instance because I changed the video model type from cirrus to vmvga so it can support a higher resolution on a console (cirrus supports up to 1280 only). After editing, i "soft-rebooted" the instance and the new configuration sticks. That's awesome.
Please don't do this :) You shouldn't change things about an instance behind nova's back. It breaks resource tracking and can cause all sorts of horribleness.
if you have support form an openstack vendor like redhat editing the domain xml also make that vm unsupported until its restroed to the way nova generated. it might also make other issue caused as a resulted unsupported. so unless you are self supporting you cloud be very carful with doing this.
But when you do a "hard-reboot" it will revert back to the original config.
Hard reboot builds configuration from scratch, dumping the existing XML. This is built from the same things used when you first create the instance (flavor + extra specs, image + metadata, host-level config, ...).
What you want is the 'hw_video_model' image metadata property. Set this and rebuild your instance:
openstack image set --property hw_video_model=vmvga $IMAGEthis is the supported way to change this value ^ it will take effect for new instances.
openstack server rebuild $SERVER $IMAGEand this is the only supported api action that can also change this value. however i dont think rebuilding to the same image will update the image metadata. you currenlty need to rebuild to a new image. this is due to an optiomisation we have to avoid needing to go to the scheuler if we use the same image.
the unsupported way to change this without rebuilding the instance is to add img_hw_video_model=vmvga to the system metadata table for that instance.
if your cloud is supported by a vendor this will also invalidate your suport in all likely hood as db modificaiton generally are unsupported without an exception. if you can rebuild the guest that is the best approch but it wont work for boot form volume instances and it willl destory all data in the root disk of all other instances.
Note that rebuild is a destructive operation so be sure you're aware of what this is doing before you do it.
Stephen
I also tried to do a "shut-down" then "start" again, but it still reads the original config. Not sure where it is reading the config from...
Regards Vlad
On Fri, Oct 30, 2020 at 12:23 PM Stephen Finucane stephenfin@redhat.com wrote:
On Fri, 2020-10-30 at 11:56 -0500, vladimir franciz blando wrote:
Hi,
I edited the libvirt xml (virsh edit...) file of a running Windows server instance because I changed the video model type from cirrus to vmvga so it can support a higher resolution on a console (cirrus supports up to 1280 only). After editing, i "soft-rebooted" the instance and the new configuration sticks. That's awesome.
Please don't do this :) You shouldn't change things about an instance behind nova's back. It breaks resource tracking and can cause all sorts of horribleness.
It is my last resort as the running Windows VM is already in production and they don't want to rebuild.
But when you do a "hard-reboot" it will revert back to the original config.
Hard reboot builds configuration from scratch, dumping the existing XML. This is built from the same things used when you first create the instance (flavor + extra specs, image + metadata, host-level config, ...).
What you want is the 'hw_video_model' image metadata property. Set this and rebuild your instance:
openstack image set --property hw_video_model=vmvga $IMAGE openstack server rebuild $SERVER $IMAGE
This is already done before I was doing it on running instances, so any new Windows VM will have it.
Note that rebuild is a destructive operation so be sure you're aware of what this is doing before you do it.
Stephen
I also tried to do a "shut-down" then "start" again, but it still reads the original config. Not sure where it is reading the config from...
Regards Vlad
participants (3)
-
Sean Mooney
-
Stephen Finucane
-
vladimir franciz blando