How to use LVM and Guests
Posted: November 7th, 2011, 6:04 pm
If you are interested in running your guest os's from a Logical Volume to reduce the wear on the hard drive, here is one simple way that I used:
First, build and install your Guest OS but make sure it is SHUTDOWN.
Second, create a raw file from you qcow os file:
This file 'disk0.raw' is also the exact size the logical volume should be. If you a nervous, make it a little bigger.
Third, go into webmin and click on Logical Volume Management under Hardware:
Create a new logical volume, specifying the size to be exactly or greater than the disk0.raw file size.
Once this is created
Ok, we're done with the conversion. Now edit the "vm1.xml" file (the file that contains the metadata for your guest). This file on my system is located:
/etc/libvirt/qemu/vm1.xml
Edit the lines:
and change them to
Last and most important step. Go into virsh. Type:
and hit enter. This will propagate the changes to qemu. Now try booting. If you did everything correctly, you now have your guest running under and LVM. This makes life a little easier!
First, build and install your Guest OS but make sure it is SHUTDOWN.
Second, create a raw file from you qcow os file:
Code: Select all
qemu-img convert /path/to/image.qcow2 -O raw /path/to/save/disk0.rawThis file 'disk0.raw' is also the exact size the logical volume should be. If you a nervous, make it a little bigger.
Third, go into webmin and click on Logical Volume Management under Hardware:
Create a new logical volume, specifying the size to be exactly or greater than the disk0.raw file size.
Once this is created
Code: Select all
dd if=/path/to/your/saved/disk0.raw of=/dev/<your volume group>/<new logical volume>Ok, we're done with the conversion. Now edit the "vm1.xml" file (the file that contains the metadata for your guest). This file on my system is located:
/etc/libvirt/qemu/vm1.xml
Edit the lines:
Code: Select all
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/var/vm2/tmpbAUtxu.qcow2'/>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' unit='0'/>
</disk>
and change them to
Code: Select all
<disk type='block' device='disk'>
<driver name='qemu' type='raw'/>
<source dev='/dev/<your volume group>/<new logical volume>'/>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' unit='0'/>
</disk>
Last and most important step. Go into virsh. Type:
Code: Select all
define /etc/libvirt/qemu/your_meta.xmland hit enter. This will propagate the changes to qemu. Now try booting. If you did everything correctly, you now have your guest running under and LVM. This makes life a little easier!