For my last job I was responsible for setting up a new virtualization environment. The original virtualization platform was RHEV and I replaced it with OpenNebula. The advantage of OpenNebula is that it is giving us a lot more flexibility and it is easy to provision new Virtual Machines from a template. Also, this is a service we could give to the developers inside the company to set up their own virtual machines.
I built a whole new environment while the old RHEV environment was still running.
On the RHEV we had a couple of Windows machines I couldn’t rebuild so I needed to migrate these to the OpenNebula environment. This was really easy as both systems are using KVM as virtualization layer. The biggest difference was that RHEV was using ISCSI and LVM as storage and our OpenNebula installation is NFS and file based.
##RHEV Manager Shell
On the RHEV machine you need to look-up some details about the virtual hard drives before you can copy them.
The first step is to make a connection to the RHEV Manager Shell.
[root@rhevmanager ~]# rhevm-shell ++++++++++++++++++++++++++++++++++++++++++ Welcome to RHEVM shell ++++++++++++++++++++++++++++++++++++++++++ [RHEVM shell (disconnected)]# connect --url "https://localhost:8443/api" --user "username" --password "password" --insecure
When connected to the RHEV Manager shell, look-up the connected disks to the virtual machine you want to copy.
[RHEVM shell (connected)]# list disks --vm-identifier test-migrate id : dff21089-e06f-46db-b5ac-fd0aef7395ba name : CentOS64_Disk1
When you have the ids of the connected disks you can also look-up the details of that disk.
[RHEVM shell (connected)]# show disk --id dff21089-e06f-46db-b5ac-fd0aef7395ba id : dff21089-e06f-46db-b5ac-fd0aef7395ba name : CentOS64_Disk1 actual_size : 10737418240 alias : CentOS64_Disk1 bootable : True format : raw image_id : 4a40e716-ea25-46e4-8f98-b7989fadb04f interface : virtio propagate_errors : False provisioned_size : 10737418240 quota-id : 00000000-0000-0000-0000-000000000000 shareable : False size : 10737418240 sparse : False status-state : ok storage_domains-storage_domain-id: 7f4acfe5-6eb7-402a-8b06-a157f8f50c0a wipe_after_delete : False
##Find the LVS
With the information you received from the RHEV Manager Shell you can find the LVS information of that disk by running the following command on the Storage Pool Manager (SPM) node.
The path exists of /dev/<storage_domains+storage_domain-id>/<image_id>
$ lvdisplay /dev/7f4acfe5-6eb7-402a-8b06-a157f8f50c0a/4a40e716-ea25-46e4-8f98-b7989fadb04f --- Logical volume --- LV Path /dev/7f4acfe5-6eb7-402a-8b06-a157f8f50c0a/4a40e716-ea25-46e4-8f98-b7989fadb04f LV Name 4a40e716-ea25-46e4-8f98-b7989fadb04f VG Name 7f4acfe5-6eb7-402a-8b06-a157f8f50c0a LV UUID 17DXHn-JLxK-hbG2-Cm93-yLGW-Pw33-9Ir95Z LV Write Access read/write LV Creation host, time node.example.local, 2014-06-10 15:06:25 +0200 LV Status available # open 0 LV Size 10.00 GiB Current LE 80 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:26
##Make the LV available
Before you can start copying the LV, you need to make the LV available for use by running lvchange with the parameters -ay (activate + yes).
$ lvchange -ay /dev/7f4acfe5-6eb7-402a-8b06-a157f8f50c0a/4a40e716-ea25-46e4-8f98-b7989fadb04f
##Copy the image
On the receiving server (OpenNebula management node) run the following command. This command will save the data it receives on port 19000 to test1.img.
$ nc -l 19000|bzip2 -d|dd bs=1M of=/test1.img
On the sending server (SPM server) execute the following command.
$ dd bs=1M if=/dev/7f4acfe5-6eb7-402a-8b06-a157f8f50c0a/4a40e716-ea25-46e4-8f98-b7989fadb04f|bzip2 -c|nc <hostname.of.server> 19000
##Import into OpenNebula
Change to user oneadmin on the OpenNebula management node and run the following command.
$ oneimage create --datastore datastore_name --name test1 --path /test1.img --description "Imported test image"
It is also possible to use the Opennebula GUI and import the copied image that way.