[NotSupported] Updating Linked VM Clones with changes to Base VM

[jrtibayan]

Hi all.. I am wondering if it is possible to update all linked clones with changes done to its base VM.
I think VMware calls this Desktop recomposition - Desktop recomposition simultaneously updates all the linked-clone desktops anchored to a parent virtual machine.
It would be great if it does have a feature similar to this.
If it doesn't I'll just settle with manually updating the clones, but if you guys have better solution I am open to trying it.
Thanks a lot in advance

[socratis]

No, you can't do it, mainly because the differencing images (aka what the clones are using) are not file-based, they're sector-based. And if you update the base VM, 1) you don't know which clusters are going to be updated, and 2) if they're going to be conflicting with an already modified cluster in the clone.

[mpack]

I don't see how this "desktop recomposition" feature could work as you want anyway. The only way linked clones could be updated from the master disk is if the linked clones disk sectors have an identical configuration as the base disk of the parent, which means that the linked clones have to be immutable or they get reset back to the state of the parent base disk, then updated.

Differential disk schemes simply don't work this way, either in VirtualBox or VMware.

Look to how these things are done in the physical world: a business network admin "pushes" software updates out over the network, each client stores the update wherever it has space. That's the only way it can be done.

[jrtibayan]

I don't see how this "desktop recomposition" feature could work as you want anyway.

Did I just misunderstood what desktop recomposition is for? Here's a reference on what I was looking at
https://pubs.vmware.com/view-51/index.j ... BE3B1.html

I was trying to find a better or easier way to update linked clones.
Is there anything to make that task easier?

[socratis]

There's nothing like that in VirtualBox natively. The only solution is the one that mpack suggested, i.e. rolling patches as if you had multiple computers around, like a business/corporate network.

[mpack]

Did I just misunderstood what desktop recomposition is for? Here's a reference on what I was looking at
https://pubs.vmware.com/view-51/index.j ... BE3B1.html

You claimed that other software had what I would consider to be magical powers , so I already did some research and saw that page. I see a lot of caveats involving features names I don't know, for example :-

"You cannot recompose desktops that are running in local mode. Local desktops must be checked in or rolled back to the datacenter before a recompose operation can take place.".

I'm going to guess that "local mode" means locally independant. Meaning it doesn't allow divergences from the master VM except temporarily (similar to immutable disks in VirtualBox).

You can easily run through the thought process yourself: imagine that that you have a working base PC. You image that PC and copy the image to a number of other PCs, which is then used by whomever. Now you update the base PC. How on earth do you push the disk changes from the base PC to all the children without messing them up? I know of no way to do it, except wipe them all and replace their disk contents with a new image (that the new image is incremental really makes no difference to this problem).

I was trying to find a better or easier way to update linked clones.
Is there anything to make that task easier?

I already described the only method I know of: updates pushed by a network admin from a local update server. It doesn't involve any VirtualBox feature.

[jrtibayan]

I see. Well I did thought of that. I just thought there are people out there that maybe could do it or already did it. I haven't really tried VMware so I have no idea if that is the feature I really am looking for, but from the description in their site it sound like that it is but I am not willing to switch to it and gonna stick with VirtualBox. I do know I can just update them using local update server like how we did it before Virtualization became a thing but since I am learning Virtualbox I'm trying to solve it with features installed with it. In this case looks like there's none so gonna stick with your suggestion.

Thanks a lot mpack and socratis. I really appreciate you answering my queries.

[socratis]

I can't see an easy way (or any way) to implement what you're suggesting with the current way that things are done, so I'm going to mark this as [NotSupported].