[pve-devel] [PATCH] Make qm clone working with devices.

[Jasmin J.]

Hi!

> In your case choosing Qcow2 as image format for your VMs seems
> appropriate since this will give you the choice of doing snapshots of your
> VMs before doing any changes and the decide after your changes whether to
> rollback the changes or delete the snapshot.
a) We discuss a patch to complete the current PVE implementation and not how
I or some else wants to use the direct device mapping. There are several
reasons why someone likes to use this. And I am very happy, that PVE supports
direct device mappings.

b) I really WANT to use the direct device mapping, because it has advantages
in speed and for migrating. I plan to use it for a WEB server and the WEB
data for the customers are stored on HW RAID volume. If I need to upgrade to
a newer Linux version, I simply clone the VM, change the IP address, use
temporarily a virtual disk for the WEB data, do the upgrade, test it as long
I want.
When all is running, I switch of the old VM, use the RAID device in the new
VM and start, with a minimum down time of 4 minutes.
And using the RAID device directly is better in performance, as far as I know.

BR,
   Jasmin

*************************************************************************

On 2014-10-26 11:27, Michael Rasmussen wrote:
> On Sun, 26 Oct 2014 11:04:40 +0100 "Jasmin J." <jasmin at anw.at> wrote:
> 
>> 
>> I intended to use cloning a VM with a device to make a copy of the 
>> current state just before I do changes in the VM (e.g: update, install 
>> new software). And yes, it might be a problem to start the cloned VM 
>> together with the original, but this is logical and depends on the file 
>> system used on the disk device. With my patch cloning is still possible 
>> only from the command line, because the WEB interface currently doesn't 
>> allow it for VMs with device disks.
>> 
> Would it not simply be easier if you choose an image format which support 
> your needs?
> 
> In your case choosing Qcow2 as image format for your VMs seems
> appropriate since this will give you the choice of doing snapshots of your
> VMs before doing any changes and the decide after your changes whether to
> rollback the changes or delete the snapshot.
> 
> 
> 
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