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Re: [Xen-Users] How to clone a VM when it is running?

To: "Xen-Users" <xen-users@xxxxxxxxxxxxxxxxxxx>, "freddie weng" <freddieweng@xxxxxxxx>
Subject: Re: [Xen-Users] How to clone a VM when it is running?
From: "Nick Couchman" <Nick.Couchman@xxxxxxxxx>
Date: Fri, 20 Mar 2009 09:35:43 -0600
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Cloning a VM while it is running isn't really a great idea.  In order to maintain filesystem consistency, at the time of the clone all filesystem activity must be frozen and data needs to be flushed from the caches and buffers out to disk devices.  If order to do this while the VM is running, you have to interact with the O/S of the VM to freeze filesystem transactions (XFS is the only filesystem I've used that supports this), flush out the buffers and caches ("sync"), then clone the disk image, then unfreeze the filesystem.  A much easier option is to pause the domU temporarily ("xm pause <domU>"), clone it, then unpause.


Why is being able to clone while a domU is running so critical to you?

>>> On 3/20/2009 at  9:26 AM, freddie weng <freddieweng@xxxxxxxx> wrote:

Hi everybody,

I found that we can use virt-clone to clone a VM but only when that VM is not running.
This is not useful most of the time.
Can we clone a VM even when it is running?

It's critical to my research, any idea is much appreciated!!!!


all the best,
Freddie



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