[vox-tech] Cloning LVM volume over network

[Alex Mandel]

On 06/03/2012 08:31 AM, timriley at appahost.com wrote:
>> -------- Original Message --------
>> Subject: Re: [vox-tech] Cloning LVM volume over network
>> From: Alex Mandel <tech_dev at wildintellect.com>
>> Date: Tue, May 29, 2012 2:09 pm
>> To: lugod's technical discussion forum <vox-tech at lists.lugod.org>
>> Cc: Brian Lavender <brian at brie.com>
>>
>>
>> On 05/29/2012 11:36 AM, Brian Lavender wrote:
>>> On Sun, May 27, 2012 at 09:16:24AM -0700, Wes Hardaker wrote:
>>>> Alex Mandel <tech_dev at wildintellect.com> writes:
>>>>
>>>>> I'm looking for the most efficient way to clone an LVM volume 50GB from
>>>>> one physical machine to another. Both machines must stay up, so that
>>>>> rules out clonezilla. I'd also like it to be more efficient that dd, so
>>>>> more similar to partimage or partclone where it skips the empty space
>>>>> and only copies the filled part.
>>>>>
>>>>> Anyone have examples that show how to do this?
>>>>
>>>> I'd typically use rsync...  Fast and efficient :-)
>>>
>>> Assuming the lvm volume is mounted on both sides and you tunnel rsync over ssh. 
>>> If you are in an internal network, you could do it over rsh and avoid the crypto
>>> overhead.
>>>
>>> cd /mnt/local
>>>
>>> Then use the the following from the rsync man page, clipped below. 
>>> rsync uses the -e option for ssh, but I don't quite have a machine to test it.
>>>
>>>  To synchronize my samba source trees use the following: 
>>>
>>>                    rsync -Cavuzb . remote_machine:/mnt/local/
>>>
>>> It is clipped from where Tridgell talks abut syncing his samba shares using
>>> a Makefile and samba source code for CVS commits.
>>>
>>> brian
>>>
>>
>> I think the tricky part here is that the lvm volume may contain multiple
>> partitions (I think it does have a / and a swap since it's a virtual
>> machine disk), and I need the partition information, including the boot
>> flags.
>>
>> Yes it is local network, same rack, I even have a private subnet between
>> the machines.
>>
>> This seems to be the foolproof way
>> http://www.alethe.com/brad/2008/04/move-an-lvm-based-virtual-machine-to-another-host/
>>
>> Was just hoping I could figure out how to do it faster, clonezilla seems
>> fancier than just partclone though. I think I need something that dumps
>> the partition information too.
> 
> What did you decide?
> 

I did get the suggestion to boot clonezilla in inside both virtual
machines and copy. That sounds like a good idea but for some reason
didn't work out because the desination Host machine locked up and
required a physical reboot. No idea why.

What I did find that was somewhat efficient and worked was using
qemu-img convert -c -f raw -O qcow2 /dev/kvm01/guest1 guest1.qcow2
which made a compressed sparse qcow2 file. So 2 GB of data in a 100 GB
lvm volume became a 1.3 GB qcow2 file in about 20 minutes. Took 2
minutes to copy over to my second host and about 20 minutes to extract
again. The + is I have a backup of the copy now too and it's small.

It did appear pipe possible but I didn't want to risk messing up such
syntax.

Thanks,
Alex