virsh snapshot-create-as fails to create external snapshot (Error from child process creating with name of memory output file)

Asked by Thierry Bouhnik on 2017-08-06


I tried for the first time to create an external snapshot and as I want to do it with vm online, ram must be saved to have a valid backup.

So I typed that:

# virsh snapshot-create-as --domain jeedom —-name jeedom_snap --diskspec vda,snapshot=external,file=/media/ds415play/donnees/Intel\ NUC/VM/jeedom/backup/jeedom_vda_snap.qcow2 --memspec file=/media/ds415play/donnees/Intel\ NUC/VM/jeedom/backup/jeedom_mem_snap.qcow2,snapshot=external --atomic

erreur : Error from child process creating '/media/ds415play/donnees/Intel NUC/VM/jeedom/backup/jeedom_mem_snap.qcow2': Opération non permise

I use Ubuntu 16.04.2 LTS and my versions of libvirt packages :

root@D54250WYK:/home/thierry# dpkg -l | grep "libvirt"
ii gir1.2-libvirt-glib-1.0:amd64 0.2.2-0.1ubuntu1 amd64 libvirt glib mainloop integration
ii libvirt-bin 1.3.1-1ubuntu10.10 amd64 programs for the libvirt library
ii libvirt-glib-1.0-0:amd64 0.2.2-0.1ubuntu1 amd64 libvirt glib mainloop integration
ii libvirt0:amd64 1.3.1-1ubuntu10.10 amd64 library for interfacing with different virtualization systems
ii python-libvirt 1.3.1-1ubuntu1 amd64 libvirt Python bindings

# libvirtd --version
libvirtd (libvirt) 1.3.1

# virsh --version

Dump of my xml config

OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
  virsh edit jeedom
or other application using the libvirt API.

<domain type='kvm'>
  <memory unit='KiB'>1048576</memory>
  <currentMemory unit='KiB'>1048576</currentMemory>
  <vcpu placement='static'>1</vcpu>
    <type arch='x86_64' machine='pc-i440fx-xenial'>hvm</type>
    <boot dev='hd'/>
  <cpu mode='custom' match='exact'>
    <model fallback='allow'>Haswell-noTSX</model>
  <clock offset='utc'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/debian_jessy.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    <controller type='pci' index='0' model='pci-root'/>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    <controller type='usb' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    <interface type='bridge'>
      <mac address='***************'/>
      <source bridge='br0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    <serial type='pty'>
      <target port='0'/>
    <console type='pty'>
      <target type='serial' port='0'/>
    <channel type='spicevmc'>
      <target type='virtio' name='com.redhat.spice.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes'>
      <image compression='off'/>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
      <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    <hostdev mode='subsystem' type='usb' managed='yes'>
        <vendor id='0x0658'/>
        <product id='0x0200'/>
    <redirdev bus='usb' type='spicevmc'>
    <redirdev bus='usb' type='spicevmc'>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>


Question information

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Solved by:
Thierry Bouhnik
Last query:
Last reply:

What is the file system mounted at /media/ds415play please?


It's a samba resource to point to my NAS, mounted with "cifs":

//ds415play.local/donnees/ /media/ds415play/donnees cifs rw,relatime,vers=1.0,cache=strict,username=thierry,domain=DS415PLAY,uid=0,noforceuid,gid=0,noforcegid,addr=*****,unix,posixpaths,serverino,mapposix,acl,rsize=1048576,wsize=1048576,actimeo=1 0 0

I already test and this location is writable from my intel nuc.


# virsh snapshot-create-as --domain jeedom —-name jeedom_snap --diskspec vda,snapshot=external,file=/home/thierry/VM/backups/jeedom_vda_snap.qcow2 --memspec file=/home/thierry/VM/backups/jeedom_mem_snap.qcow2,snapshot=external --atomic
Domain snapshot —-name created

You were right, it works now.

So it's incompatible with cifs mount ? :(


Possible. That's why I ask. You could try moving it to cifs then move it back then try using the file.
File systems are weird sometimes. You get a lot of folks trying NTFS and it doesn't hold Linux permissions. Not sure why you can't use CIFS

Ok, thanks.

Another question if it's possible in this thread, even if it's not the same as origin :

I try to active the original image with:
virsh blockcommit jeedom vda --active --verbose --pivot

But with that command, I see alway that
# virsh snapshot-list jeedom
 Nom Creation Time État
 —-name 2017-08-07 21:19:55 +0200 running

it means that it's always running?
It seems that this VM was called "—-name".

 virsh domblklist jeedom
Target Source
vda /var/lib/libvirt/images/debian_jessy.qcow2

It seems that the main image was coming back so I could try to delete that snap test.

I tried to delete it without success with
 virsh snapshot-delete --domain jeedom --snapshotname —-name
erreur : Failed to delete snapshot —-name
erreur : unsupported configuration: deletion of 1 external disk snapshots not supported yet

How could I do to delete it without risk as " virsh domblklist jeedom" show my main VM?

Remove manually xml file and files in VM/backups/ ?

Could I open a bug for this problem of deletion?

Thanks :)

Problem also resolved:
 virsh snapshot-delete --domain jeedom --metadata —-name
Domain snapshot —-name deleted

Many thanks for all.