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klaus thorn's questions

Martin Hope
klaus thorn
Asked: 2018-08-18 01:42:24 +0800 CST
  • 1

So I have just added a firewall rule using ufw. How do I know whether I have to do additional steps to make this rule also automatically present after reboot?

(2nd question, but less important to me: If they are needed, which steps?)

For example: Do I have to check for installed/enabled/configured iptables-save? Do I have to put the rule into /etc/ufw/? (where?) Is there a rule like: If I am using Ubuntu, then ufw will always remeber state after reboot?

I am not used to work with ufw or iptables-save. I just read rumors in forums and the man page for ufw.

If you have to assume an operating system for your answer then please assume Ubuntu 16.04.

firewall
Martin Hope
klaus thorn
Asked: 2016-09-24 01:56:30 +0800 CST
  • 1

When creating the virtual machine on server A, virt-install created a libvirt-volume "VM" in the libvirt storage-pool "POOL".

 virsh-install --disk pool=POOL,size=$HDDSIZE,$DISKOPT -n VM

As expected, libvirt shows e.g.

# virsh vol-list POOL

Name                 Path
-----------------------------------------
VM                  /dev/VOLUMEGROUP/VM
anotherVM           /dev/VOLUMEGROUP/anotherVM

When migrating the virtual machine to server B, which does not share storage with server A, I instead created the logical volume with lvm:

 lvcreate -l $EXTNSIZE -n lvmVM VOLUMEGROUP

As not expected (but arguably expectable), libvirt on server B does not recognize lvmVM.

# virsh vol-list POOL

Name                 Path
-----------------------------------------
someOtherVM         /dev/VOLUMEGROUP/someOtherVM

I was able to manually start VM anyway. Fine. But...

  • Are there dangers/disadvantages to leave libvirt in a blind state about the new volume inside POOL like this?
  • e.g. will libvirt fail to auto-restart the VM on reboot etc.?

(or, from the other perspective: What is the gain in using libvirt volumes instead of just lvm volumes inside a storage pool, after the initial creation via e.g. virt-inst?)

  • Is there a way to make libvirt recognize the volume?
  • ... but would this recognition/conversion process write metadata into lvmVM and thus corrupt the VM virtual disk?

Details:

  • On both servers, the lvm group "VOLUMEGROUP" is used for libvirt storage pool "POOL".
  • On both servers, lvm shows the expected volume. Just the libvirt volume-"layer" is different.
  • Debian Linux 8 x86_64, lvm2 2.02.111-2.2+deb8u1, libvirt 1.2.9-9+deb8u3
  • size is 40 GB, DISKOPT='bus=virtio,cache=writethrough,io=threads,sparse=false'
  • beneath libvirt, KVM and qemu are used.

  • libvirt xml for virtual machine "VM" has:

    disk type='block' device='disk' 
 driver name='qemu' type='raw'
 source dev='/dev/VOLUMEGROUP/VM'
 target dev='vda' bus='virtio'
lvm libvirt