Re: [Engine-devel] Floating Disks implementation in REST-API
> Floating disks should be both in the root context, and also in
the VM
> context for each VM the floating disk is attached to, right? So floating
> disks would appear 1+N_attach times in the API, once in the root
> context, and once for each VM they are attached to.
>
IIUC a floating disk is not associated with the VM in any way, and should
not appear in that VM's collection of disks. There's a similar feature of
activate/deactivate disk (http://www.ovirt.org/wiki/Features/HotPlug).
A deactivated disk is still associated with the VM, and should appear in
the VM's collection of disks. Perhaps this is the source of confusion.
No that isn't it. I think have a bit of terminology mismatch. According to:
http://www.ovirt.org/wiki/Features/DetailedFloatingDisk
i think your use of the word floating is correct. I got confused as i
thought that any disk could be floating, whether it was attached to 0
VMs, 1 VM, or 2 or more VMs.
So before we go further, let's get things straight:
- disk without any VMs => floating. It appears in the root context.
- disk attached to 1 VM => normal state. It appears in the VM context.
- disk attached to 2 VMs => shared disk. It appears in both VM contexts.
Is that correct?
Also can someone explain on how floating and shared disks are actually
implemented in the BE? I imagine it's one of two ways:
=> The BE keep a global list of disks, each disk with zero or more
references to a VM.
=> The BE keeps a special "floating" state independent of the number
of VMs that it is attached to.
Thanks,
Geert