Differences

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--- libvirt:libvirt [2014/08/07 09:36] – [Store] deva
+++ libvirt:libvirt [2016/09/15 21:18] (current) – deva
@@ Line 1: / Line 1: @@
 ======Libvirt======
+=====Resize qcov2 image=====
+<code>
+# Shut down vm
+# On host (to grow 8GB):
+qemu-img resize /images/myimage.qcow2 +8GB
+# Start vm
+# Assuming lvm logical volume inside extended partition...
+# fdisk -l should now show the new disk size.
+# run parted
+(parted) resizepart 2
+GB
+(parted) resizepart 5
+GB
+(parted) quit
+# resize volume group
+pvresize /dev/sda5 # on lvm partition
+# extend lvm
+lvextend -l +100%FREE /dev/mapper/devuan--vg-root
+# finally resize file system
+resize2fs /dev/mapper/devuan--vg-root
+</code>
+=====List VMs=====
+<code>
+virsh list --all
+</code>
 =====Copy a VM=====
@@ Line 32: / Line 63: @@
 cd /my/backup/dir/foobar
-# Pause the VM
+# Dump the state (memory, network etc...)
-virsh suspend foobar
+virsh save foobar foobar.state
 # Dump the VM configuration
@@ Line 42: / Line 73: @@
 virsh dumpxml foobar | grep '\.img'
 cp /location/of/image/foobar.img .
+</code>
-# Dump the state (memory, network etc...)
+At this point the complete VM state has been stored but the VM is stopped.
-virsh save foobar foobar.state
+In order to resume the VM from the point where it left off, it must be resumed from the just saved state:
+<code>
+virsh restore foobar.state
 </code>
+**IMPORTANT**: After restoration, the VM will have its RTC (clock) set to whatever it was on store time. This means that the clock will be out of sync by probably a couple minutes (depending on how long it took to copy the virtual harddisk) and this must be handled by the VM by for example using ntpd.
+**NOTE**: Using ntpd to sync a clock that is more than a matter of seconds out-of-sync might require special attention to its config file as it might refuse to synchronize the clock because it is too much out of sync.
+FIXME: Use "virsh blockcopy" for harddrive backup, which will reduce downtime to a matter of seconds in the VM.
 ====Restore====
 <code>
@@ Line 60: / Line 99: @@
 # Restore the state (memory, network etc...)
 virsh restore foobar.state
-# Resume the VM
-virsh resume
 </code>
+**WARNING**: After restoration the rtc (clock) will be set to whatever it was on store time. Set the date manually by calling ntpdate (on centos call: "service ntpdate start")