that the most precious commodity in the apocalypse would be toilet paper?

View all of Who would've thought...

Newer versions of XenServer expect you to use vApps to handle virtual machines auto starting.  This may not be appropriate in some situations.

You can still enable auto-power on via command line on the host [https://support.citrix.com/article/CTX133910], however this just batch starts all VMs at once. You might like a bit more control, particularly if you require the VMs to start up in a particular order.

The method I'm about to explain may not be particularly elegant, but it works for my home lab.

Establish a shell connection to your XenServer / XCP-NG host via SSH or directly on the console. Using PuTTY or some other SSH client that allows you to copy and paste will be really helpful.

You should be in the root user's home directory /root. This should be the default directory you're dropped in to when you first establish your connection

• otherwise just type cd and press enter to go straight there.

Create a new file called vm-autostart.sh with your favourite editor. I like vi as it's usually available.

Paste the following contents and modify the array called vms to suit:

#!/bin/bash

# xe vm-list for name-label, add in start order
vms=("VM1" "VM2" "VM3" "VM4" "VM5" "VM6" "VM7" "VM8" "VM9" "VM10")
wait=42s

# No need to modify below
initwait=2.5m
vmslength=${#vms[@]}
log=/root/vma.log

start_vm () {
   echo -n "[$(date +"%T")] Starting $1 ... " >> ${log}
   /opt/xensource/bin/xe vm-start name-label=$1
   if [ $? -eq 0 ] 
     then 
       echo "Success" >> ${log}
     else 
       echo "FAILED" >> ${log}
   fi

   # Wait if not the last vm
   if [ "$1" != "${vms[${vmslength}-1]}" ]
     then
       echo "Waiting ${wait}" >> ${log}
       sleep ${wait}
   fi
}

echo "[$(date +"%T")] Running autostart script (Waiting ${initwait})" > ${log}
sleep ${initwait}

for vm in ${vms[@]}
do
  start_vm ${vm}
done

echo "[$(date +"%T")] Startup complete." >> ${log}

The vms array takes the list of VM name-label properties. You can see them on the host if you run xe vm-list, or just take a look at your management software for the VM name. If you prefer to use the UUID, just modify the script accordingly.

The wait variable is set at 42 seconds. This is just slightly longer than it takes each of my vms to start up. You may require a bit longer, or you can set it a bit shorter. As my VMs all boot from the hosts local disks, I have the delay set so that there isn't so much contention for disk access. If you're booting from a storage array, then you might not require such a long delay.

The initwait variable is set at 2.5 minutes. This is to allow time for the toolstack to finish starting before trying to start the first VM. If the toolstack hasn't properly started before the first VM attempts to boot, the virtual machine will fail to start and you will have to start it manually. Subsequent machines will usually start, depending on the wait variable.

Save the script and quit the editor when you're happy with it. Remember to set the script to be executable with chmod a+x vm-autostart.sh.

Edit /etc/rc.d/rc.local with your favourite editor.

At the bottom of the file, add a call to your newly create and executable script:

/root/vm-autostart.sh

Save the file and quit the editor.

Make the rc.local script executable:

chmod a+x /etc/rc.d/rc.local

Next time your host restarts, your vms should start automatically. Remember to test the script manually by shutting down all your VMs and then running the script in the shell to see that you didn't inadvertently introduce any errors.

You can track the progress of the script. As soon as your host has rebooted, connect to the shell and either run tail -f /root/vma.log or run less /root/vma.log and press the F key to get the tail (Follow) function.

View all of XenServer / XCP-NG VM AutoStart

In the interest of having this information somewhere handy: Firstly, to successfully install VirtualBox Guest Additions within a server based image:

sudo apt-get install dkms build-essential linux-headers-`uname -r`

I discovered that if you clone an ubuntu server based image, networking stops functioning in the clone. The reason for this is that the new Machine assigns a new MAC address to the NIC. So the Udev rules think it's a new card, and assign it a new device id, like eth1, or eth2, etc.

To prevent this from happening, in your base image, edit /lib/udev/rules.d/75-persistent-net-generator.rules

Search for 'xen', and you'll see a block about ignoring the Xen virtual interfaces. Add the following below it:

 # ignore VirtualBox virtual interfaces
    ATTR{address}=="08:00:27:*", GOTO="persistent_net_generator_end"

Save it, and then remove the file /etc/udev/rules.d/70-persistent-net.rules.

Do the same thing in any cloned images with broken networking, and reboot the VMs.

View all of VirtualBox - Cloning Ubuntu (or Debian) based image issues

You've been messing about in your VM, installing and removing software, etc. Your disk space usage inside your machine says you've only used 3Gb of disk space, yet your actual image is much bigger. How do you fix it?

It's fairly simple to fix. First, you should probably remove all the unnecessary crap that you never use. There's a bunch of utilities out there that can help you with this.

Defrag your drive using your favourite defragger.

Now you will need one of two possible utilities (There may be more, but these are the ones I'm aware of):

• SDelete from http://www.sysinternals.com – this is a tiny 47kb executable.
• Precompact.iso – Obtained from Microsoft Virtual Server installation (May be available in other MS VM products)

Precompact.iso is MUCH easier to use. All you need to do is mount the ISO inside your VM, and it will prepare your disk for compaction.

SDelete is only marginally more difficult. Run it in a command prompt like so: SDelete -c C: (or use whatever drive letter you want to compact). SDelete will write zeroes to the free space on your drive image. This allows compaction to take place properly.  Note – this is exactly what the Precompact.iso does, just without the fancy Windows GUI progress bar.

As soon as Precompact or SDelete is finished, shut down the VM.

Open command prompt on your host machine, and navigate to the folder where your hard disk images are located.

NOTE: It's probably MUCH easier to have the path to Virtual Box set in your PATH statement, otherwise you have to specify the full path to VBoxManage every time you use it.

In the command prompt, run:

[path to virtualbox]\VBoxManage modifyhd "Name Of Image.vdi" --compact

Your disk image will now be compacted, and should end up quite a bit smaller than it was. If you get an error about the disk image not being found blah blah, specify the FULL path to the image, like so:

[path to virtualbox]\VBoxManage modifyhd "C:\Users\Username\.VirtualBox\HardDisks\Name of Image.vdi" --compact

View all of Virtual Box - Compacting Images

Like a tool, and not thinking ahead, I created an XP Base dynamic image of max 10gb in size.  While this is usually enough space to mess around with things, I find it can be a pain in the backside when you want to install a sizeable program – say Visual Studio. While possible, you end up with very little disk space left over at the end of the day.

A possible solution to this dilemma would be to simply add a new disk to the machine, as needed. However, I like making things difficult for myself, so I rather wanted to resize the initial disk.  Unfortunately this is not possible with the provided VBoxManage utility. So, you need to jump through a few hoops, but it's really not that difficult.

You will need:

• Clonezilla – http://clonezilla.org
• GParted – http://sourceforge.net/projects/gparted/

Download the ISO versions – and for Clonezilla – DO NOT download the "Alternate" version, it will NOT work.

Using the Virtual Media Manager, create a new dynamic disk of your desired larger size. Call it whatever you like. While you are there, add the CloneZilla and GParted iso's to the CD/DVD library. Create a new VM, but do not attach any disks to it. Configure it as Linux, Debian. I called mine Clone Master.

Edit the VM settings, go to the Storage node, and add a new hard disk. Select your SOURCE disk (The disk  you want to enlarge). Add another hard disk, and select the DESTINATION disk (the big image you just created). Click the CD node, and select the clonezilla image. Boot the new VM.

The CloneZilla CD should now boot (If it doesn't, check the boot priority in your VM settings, and make sure CD is set to boot first).

Use the utility to do a local disk to disk clone. Using "beginner" mode is fine.  The "expert" mode has a setting to extend the partition to the size of the destination disk, but it didn't work for me at all – the cloned partition was the original size. Not sure if it's because of the NTFS partitions, or a bug in the version I was using. If it works for you then EXCELLENT – you won't need to do the GParted segment.

Once you have cloned the disk, power off the cloning VM, edit the settings, and detach the hard disks from it. Attach the newly cloned bigger image to your original VM, or create a new VM for it, and boot it. Check that the system works ok. If the partition hasn't grown to fill the new partition, you will need to continue to the next step.

Shut down the VM with the new large image. Edit the settings of your cloning VM, set the CD to use the GParted iso, and attach the newly cloned image to the machine. Boot the machine, and GParted should load. Just accept default settings, and eventually X-Windows will load with a copy of GParted. Click the extend button, and increase the partition to fill the disk. Apply the changes. It will only take a few seconds to completed. Exit the system, and shut down the VM. Edit the VM settings, and detach the disks (It's not strictly necessary – more of a safety measure).

Boot your previous VM to test the disk. All should be good.

View all of Virtual Box - Resizing Disk Images