Small is Beautiful

Since a lot of our work lately has been based on working with RHEV and NagiosXI I wrote a small howto for converting and importing a vmware vmdk image into RHEV. The procedure details how to import into RedHats RHEV virtualization product but the converted image can be used across any KVM enabled server.

Since RHEV at its present version does not include import tools the above procedure is useful for those that need to migrate from one solution to another.

————

For those using Red Hat Enterprise Virtualization here is what I hope to be an understandable procedure for migrating your vms. The idea is to create a new vm in RHEV with a preallocated hard disk the same size or larger than the one to be imported. From here we just need to identify where the vm’s disk are located in the rhev datacenter hierarchy and copy over our converted vm.

First you must convert your nagiosXI image to qcow2 in order for RHEV to import it. This is accomplished by issuing the following command:

Code:
# qemu-img convert -O qcow2 nagiosxi-kvm.img

On the RHEV manager

1. Create a new virtual machine from the RHEV manager interface.

1.a. Select RHEL 5.x as the operating system.

2. Configure network interfaces and hard disks

Note: The RHEV Guide Me wizard will pop-up after creating the vm.

2.a. Select Configure Network Interfaces and select the network and type. When selecting the netowrk type (drivers) you can use any of the provided drivers including RedHat VirtIO (recommended) as they are included in NagiosxI.

2.b. Select Configure Virtual Disks and make sure you configure your new disk to be exactly the same size or larger than the size of the NagiosXI virtual disk. In our test environment we created a 20 GB disk. Make sure that you keep the type (driver) to IDE and select preallocated disk!

Note: The hard disk must be at least the same size as the one to be imported and preallocates.

3. Identify your newly created vm and associated disk(s) in RHEVM datacenter.

NOTE: I am assuming you only have one DataCenter. If you have more than one you need to identify the ID of the datacenter that you wish to migrate into.

3.a. Using the RHEV Manager Scripting Library display your vm’s id:

Code:
PS C:\> $vm=select-vm(”Name=“)
PS C:\> $vm

VmId : 1c657f20-1d64-4bff-9084-93530962040f
Name : w2k30-02
Description :
HostClusterId : 1
TemplateId : 2108f097-8993-4edf-b423-a81344aef747
…

From the above note the VmID.

3.b. Using the RHEV Manager Scripting Library display your vm’s disk id(s):

Code:
PS C:\> $vm.getdiskimages()

CreationDate : 12/25/2009 7:56:57 PM
LastModified : 12/25/2009 7:56:57 PM
ActualSizeInSectors : 1048576
ActualSizeInMB : 512
ActualSizeInGB : 0
Description : VDC_w2k30-02_12/25/2009 5:54:46 PM
SnapshotId : 46e8f0df-b41f-42c5-82fe-ad808f22ef52
VmSnapshotId : a6e9fad2-e5f6-4343-be5f-5fb79d275654
SizeInGB : 10
…

From the above command note the SnapshotID

The following is to be executed on one of your RHEV hosts (physical servers).

3.c. Navigate to your vm’s directory on one of your RHEV hosts.

Now to find out where the datacenter is mounted run the mount command and note the output. Look for rhev in the output.

Code:
# mount

….
192.168.0.162:/srv/iso on /rhev/data-center/mnt/192.168.0.162:_srv_iso type nfs (rw,soft,timeo=10,retrans=6,addr=192.168.0.162)
/dev/mapper/8233a333–d7cb–4b1d–9639–143b9ad68f98-master on /rhev/data-center/mnt/blockSD/8233a333-d7cb-4b1d-9639-143b9ad68f98/master type ext2 (rw)
….

In our particular case it is the second entry that contains our datacenter. Your output will differ based on the technology used (NFS,FCP,iSCSI)..

3.d. Change to the vms directory.

Code:
# cd /rhev/data-center/mnt/blockSD/8233a333-d7cb-4b1d-9639-143b9ad68f98/master/vms

3.e. Enter your vm’s directory. This is the VmID noted in step 3.a.

# cd

In this directory you will find the configuration file for your vm (VmID.ovf) and symbolic link to your disks. List the contents of the symbolic link and look for the SnapshotID you noted earlier. This is your disk.

4. Copy your nagiosxi-kvm.img image over to this server (scp,etc.) and dd it over the disk we just identified.

Code:
# dd if=/path/to/nagiosxi-kvm.img of=/rhev/data-center/…./disk-id

That’s it. Now you should have functional NagiosXI vm ready to use from within RHEV.

If things are not clear please let me know and Ill try to clear them up

Good luck.

———
I used the following link to convert from vmdk to qcow2. [LINK]
The following link is the howto located in the nagiosxi support forums. [LINK]

This entry was posted on Saturday, January 2nd, 2010 at 5:43 pm and is filed under Tech. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.