[Users] Templates and originating VM relationship
Hello, oVirt 3.2.1 on Fedora 18. I customize a CentOS 6.4 VM and when I comfortable I select "make template". I don't take any snapshot for the VM before this. I thought that VM would have been disappeared, transforming itself into a template, instead at the end I have both the template and the originating VM. Apparently with the same name for the disk and the same storage domain.... What is exactly the relationship between them? Can I safely remove the originating VM? I already tested making template and then deleting it and then being able to power on again VM and make a new template from the originating VM. The rhevm 3.1 admin manual is not so clear about this: it contains a note regarding " Take a snapshot of the virtual machine at this stage if you wish to use the virtual machine (as a virtual machine) after using it to create a template. " But if behavior of oVirt 3.2.1 has to be the same with it, this doesn't explain itself based on my experience.... Thanks in advance for any information Gianluca
Hi Gianluca, @oVirt-team: please correct me if I misunderstood something on the template-concept... Unlike Vmware (which converts a vm into a template) RHEV/oVirt is copying the vm into a template. So you can remove or edit your original vm without having an impact on your template. More important is the template provisioning method when creating vms from your template. If you choose Thin, only changes between your template and your vm are written to your vms disk file, where clone creates a clone of your template's disk. Template thin provisioning saves disk space, but you can't delete the template as long as you don't delete all vms linked to this template. The name of your disk is just a name (and it seems that it doesn't have to be unique) - important is the ID, which is used by oVirt internally. Regards, René On Tue, 2013-03-26 at 15:11 +0100, Gianluca Cecchi wrote:
Hello, oVirt 3.2.1 on Fedora 18. I customize a CentOS 6.4 VM and when I comfortable I select "make template". I don't take any snapshot for the VM before this.
I thought that VM would have been disappeared, transforming itself into a template, instead at the end I have both the template and the originating VM. Apparently with the same name for the disk and the same storage domain....
What is exactly the relationship between them? Can I safely remove the originating VM?
I already tested making template and then deleting it and then being able to power on again VM and make a new template from the originating VM.
The rhevm 3.1 admin manual is not so clear about this: it contains a note regarding " Take a snapshot of the virtual machine at this stage if you wish to use the virtual machine (as a virtual machine) after using it to create a template. "
But if behavior of oVirt 3.2.1 has to be the same with it, this doesn't explain itself based on my experience....
Thanks in advance for any information
Gianluca _______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
On Tue, Mar 26, 2013 at 3:41 PM, René Koch (ovido) wrote:
Unlike Vmware (which converts a vm into a template) RHEV/oVirt is copying the vm into a template.
So you can remove or edit your original vm without having an impact on your template.
OK. So the note in Procedure 9.1 at page 162 of RHEV 3.1 admin guide is not correct....
More important is the template provisioning method when creating vms from your template. If you choose Thin, only changes between your template and your vm are written to your vms disk file, where clone creates a clone of your template's disk. Template thin provisioning saves disk space, but you can't delete the template as long as you don't delete all vms linked to this template.
This was clear to me based on manual contents, but thanks for the remainder. Gianluca
On Tue, 2013-03-26 at 15:50 +0100, Gianluca Cecchi wrote:
On Tue, Mar 26, 2013 at 3:41 PM, René Koch (ovido) wrote:
Unlike Vmware (which converts a vm into a template) RHEV/oVirt is copying the vm into a template.
So you can remove or edit your original vm without having an impact on your template.
OK. So the note in Procedure 9.1 at page 162 of RHEV 3.1 admin guide is not correct....
I didn't had issues when creating templates from vms without snapshots and reusing the vm again. I think it's because of sealing/sysprep. Let's assume you create a template of a windows vm, I would do the following steps: 1. Install all apps and settings in your vm 2. Take a snapshot of this vm 3. sysprep your vm 4. Create a template 5. Revert to previous snapshot when reusing your vm, as otherwise sysprep would start (and you don't want it for your master-image).
More important is the template provisioning method when creating vms from your template. If you choose Thin, only changes between your template and your vm are written to your vms disk file, where clone creates a clone of your template's disk. Template thin provisioning saves disk space, but you can't delete the template as long as you don't delete all vms linked to this template.
This was clear to me based on manual contents, but thanks for the remainder.
Gianluca
Hello, I'm from the RHEV docs team. Gianluca, thanks for reading the docs. :) If I can summarize what you've noticed, its that the note there is not needed. https://bugzilla.redhat.com/show_bug.cgi?id=954211 Also, it would be good to add something about the relationship between the original VM and the template after a template has been created, is that right? https://bugzilla.redhat.com/show_bug.cgi?id=954215 Can you comment on those bugs and let me know if I've missed anything, or if there is anything else you'd like to see? Thanks again Gianluca. Tim Hildred, RHCE Content Author II - Engineering Content Services, Red Hat, Inc. Brisbane, Australia Email: thildred@redhat.com Internal: 8588287 Mobile: +61 4 666 25242 IRC: thildred ----- Original Message -----
From: "René Koch (ovido)" <r.koch@ovido.at> To: "Gianluca Cecchi" <gianluca.cecchi@gmail.com> Cc: "users" <users@ovirt.org> Sent: Wednesday, March 27, 2013 12:59:50 AM Subject: Re: [Users] Templates and originating VM relationship
On Tue, 2013-03-26 at 15:50 +0100, Gianluca Cecchi wrote:
On Tue, Mar 26, 2013 at 3:41 PM, René Koch (ovido) wrote:
Unlike Vmware (which converts a vm into a template) RHEV/oVirt is copying the vm into a template.
So you can remove or edit your original vm without having an impact on your template.
OK. So the note in Procedure 9.1 at page 162 of RHEV 3.1 admin guide is not correct....
I didn't had issues when creating templates from vms without snapshots and reusing the vm again.
I think it's because of sealing/sysprep.
Let's assume you create a template of a windows vm, I would do the following steps: 1. Install all apps and settings in your vm 2. Take a snapshot of this vm 3. sysprep your vm 4. Create a template 5. Revert to previous snapshot when reusing your vm, as otherwise sysprep would start (and you don't want it for your master-image).
More important is the template provisioning method when creating vms from your template. If you choose Thin, only changes between your template and your vm are written to your vms disk file, where clone creates a clone of your template's disk. Template thin provisioning saves disk space, but you can't delete the template as long as you don't delete all vms linked to this template.
This was clear to me based on manual contents, but thanks for the remainder.
Gianluca
_______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
On Mon, Apr 22, 2013 at 2:01 AM, Tim Hildred wrote:
Hello,
I'm from the RHEV docs team.
Gianluca, thanks for reading the docs. :)
no problem. It's only part of double direction contribution in opensource style ;-)
If I can summarize what you've noticed, its that the note there is not needed. https://bugzilla.redhat.com/show_bug.cgi?id=954211
Ok, I updated the bugzilla with my considerations.
Also, it would be good to add something about the relationship between the original VM and the template after a template has been created, is that right? https://bugzilla.redhat.com/show_bug.cgi?id=954215
Part of its considerations already put in above bugzilla. Still it can be useful to create a separate paragraph with details about hw of template (nic, disk, ecc.) vs the original vm Gianluca
participants (3)
-
Gianluca Cecchi -
René Koch (ovido) -
Tim Hildred