[DRBD-user] Geo-mirroring an active LVM volume with drbd

Paul drbd at comm.it
Fri Apr 10 10:18:32 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hi all,

I've been away from drbd for some time now (last I was using version  
6), but how I have a project that could be usefull to many people (I  
hope).

I'm trying to use drbd to create a mirror of a running LVM volume to a  
remote site over a wan connection.

The LVM volume holds the image of a windows system running in a xen  
hvm host. My aim is to move this virtual machine accross data centers  
with no downtime. Just move it while running and then shut it down in  
the old center and power it on in the new center.

To accomplish this I need to enslave the lvm holding the machine to  
drbd and then replicate it to the new datacenter. However, there are a  
number of problems that I envision along the way.

If I "enslave" a physical lvm volume to drbd, will it overwrite any  
region of the underlying lvm (possibly destroying the host partition  
table there) ?

Is there a way to use an external "map" so to preserve the original  
lvm volume?

if the original lvm volume cannot be preserved, should I just create a  
new physical volume to the VG with another drbd device and then just  
pvmove the extents from the old PV to the new drbd PV which will then  
simply replicate to the new datacenter? and then do the reverse  
offloading the drbd PV to a local PV in a local san storage?

Any other ideas whould be really appreciated... as I have to move  
several hundred GB and they will take some days to replicate via WAN.

Cheers,
Paul.



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