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Role access

Only administrators have access to this feature.

Types of hypervisors

Pure hypervisor

When you edit or create an hypervisor you can check if it will be only an hypervisor. In this mode that server will only be used by IsardVDI to run virtual desktops. No virtual disks operations will be handled by this server.

Pure disk operations

In this mode the server will only be used to handle virtual desktops disk operations.

Mixed hypervisor + disk operations

This mode will use the server for both running virtual desktops and executing virtual disk operations.

External hypervisors

The preferred method for setting up a new hypervisor is to use the docker isard-generic-hyper image as it will bring up all the services needed in any linux host with docker. Three steps are required:

  1. Install KVM hypervisor (docker recommended)
  2. Add ssh keys for new KVM hypervisor
  3. Create new hypervisor in IsardVDI web UI.

Install KVM hypervisor

Docker Install (preferred)

Quick and easy setup of an external hypervisor could be done by using the ./ hypervisor hypervisor.yml generated compose file. In your clean Linux installed server that will be the KVM hypervisor start container:

./ hypervisor
docker-compose -f hypervisor.yml up -d

Remember to configure isardvdi.cfg file prior to building hypervisor.yml file.

Mainly you can set up there your video letsencrypt domain (if not it will use autogenerated certificate). That should bring up a complete Isard Hypervisor in your server.

If you are not setting a letsencrypt configuration in isardvdi.cfg file then you need to set up the same viewers certificates in all hypervisors. In this case you should copy /opt/isard/certs/viewers/* certificate files from web host to the same folder in your remote hypervisors (removing the ones already there) and bring hypervisor docker up again.

Run this command to reset ssh keys and password:

docker exec -e PASSWORD=<YOUR_ROOT_PASSWORD> isard-hypervisor bash -c '/'

After that you can continue to add ssh keys for this hypervisor in your IsardVDI isard-engine container and create new hypervisor in UI:

docker exec -e HYPERVISOR=<IP|DNS> -e PASSWORD=<YOUR_ROOT_PASSWD> -e PORT=2022 isard-engine bash -c '/'; history -d $((HISTCMD-1))

Manual Install

If you want to use another host as the KVM hypervisor ensure it has:

  • libvirtd:
    • service running: systemctl status libvirtd. Check with your distro how to install a complete KVM hypervisor:



    • certificates enabled: Actual certificates on IsardVDI path /opt/isard/certs/default/ must be copied to your new KVM server path /etc/pki/libvirt-spice. Also some lines should be added to libvirtd.conf and qemu.conf to make use of the certificates:

    • bash echo "listen_tls = 0" >> /etc/libvirt/libvirtd.conf; echo 'listen_tcp = 1' >> /etc/libvirt/libvirtd.conf; echo 'spice_listen = ""' >> /etc/libvirt/qemu.conf echo 'spice_tls = 1' >> /etc/libvirt/qemu.conf

    • websocket server: In order to allow connection to viewers through browsers also a websocket server should be set up. You should look at the included dockers/hypervisor.

    • sshd service running and reacheable for user: systemctl status sshd
    • curl: It will be used to get updates.
    • qemu-kvm: You should create link to your qemu-system-x86_64 like this ln -s /usr/bin/qemu-system-x86_64 /usr/bin/qemu-kvm

Add ssh keys for new Hypervisor

You should previously add ssh keys to access that hypervisor. We do provide an script inside isard-app container to do this:

docker exec -e HYPERVISOR=<IP|DNS> -e PASSWORD=<YOUR_ROOT_PASSWD> isard-engine bash -c '/'

Note: There are optional parameters that can be set:

  • PORT: Default is 22
  • USER: Default is root

After doing this you should go to hypervisors menu and add a new hypervisor with the same IP/DNS. Engine will try to connect when you enable that hypervisor.


Note that we added ; history -d $((HISTCMD-1)) to the command to avoid password being kept in our history.

root@server:~/isard# docker exec -e HYPERVISOR= -e PASSWORD=supersecret isard_isard-app_1 bash -c '/'; history -d $((HISTCMD-1))
(1/1) Installing sshpass (1.06-r0)
Executing busybox-1.28.4-r2.trigger
OK: 235 MiB in 127 packages
Trying to ssh into
# SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.1
# SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.1
# SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.1
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
expr: warning: '^ERROR: ': using '^' as the first character
of a basic regular expression is not portable; it is ignored

/usr/bin/ssh-copy-id: WARNING: All keys were skipped because they already exist on the remote system.
        (if you think this is a mistake, you may want to use -f option)

Hypervisor ssh access granted.
Access to granted and found libvirtd service running.
Now you can create this hypervisor in IsardVDI web interface.

If it fails, disable hypervisor, edit parameters and enable it again. IsardVDI engine will check connection again. You can see failed message in hypervisor details (click on + button to see details).

If engine is not trying to connect again after enabling the new hypervisor, restart the isard-app container:

docker restart isard_isard-app_1

NOTE: Probably you want to remove default isard-hypervisor after creating a new external hypervisor. Disable isard-hypervisor and delete from hypervisor details. A Force delete action and isard-app container restart may be done afterwards.

Add hypervisor in web UI

An external hypervisor can be added in the web UI as an admin user. To do this you have to go to the administration panel and in the "Hypervisors" section, press the "Add new" button

And a dialog window will appear where you can fill in the fields. Anything can be configured in the ID field to identify this hypervisor, but care must be taken with other configuration fields, as they must match the remote hypervisor:

Hostname should be the IP/DNS reacheable from this IsardVDI installation. It could be an internal network between both hosts. The user will be root and ssh port 2022 as we left default ssh port 22 for ssh access to the host.

Recommended to activate disk operations and hypervisor options and set web host to this web installation IP/DNS host and video proxy to the IP/DNS externally reacheable for the hypervisor (access to their viewers through ports 80 and 443).

Set hypervisor hostname from video proxy to isard-hypervisor as it is the container name for hypervisor defaults.

VLANS in hypervisor

To connect a trunk interface with vlan definitions inside the hypervisor you have to set (and uncomment) variables in the isardvdi.cfg file:

IMPORTANT NOTE: Remember to rebuild the docker-compose by issuing the ./ command again.

  • HYPERVISOR_HOST_TRUNK_INTERFACE: This is the host network trunk interface name as seen in the host. For example: eth1

If you don't set HYPERVISOR_STATIC_VLANS the hypervisor will auto detect vlans for 260 seconds each time it starts isard-hypervisor container. So, it is better to define the static vlans you know are in the trunk.

  • HYPERVISOR_STATIC_VLANS: Set a list of vlan numbers comma separated. Setting this will avoid autodetecting vlans for 260 seconds.

This will add into the database the found vlans as 'vXXX' where XXX is the vlan number found. For this to work you should check that STATS_RETHINKDB_HOST can be reached at port 28015 from the hypervisor.

Check that you have the correct hostname for the one holding the isard-db. This is only needed if you have the hypervisor in another machine:

  • STATS_RETHINKDB_HOST: Set it to your correct isard-db host if you have the hypervisor in another machine. Not needed if you have an 'all-in-one' IsardVDI.

NOTE: The host interface should be in promiscous mode: ip link set dev ethX promic on. If the isard-hypervisor container is started you have to stop it and start it again.

Infrastructure concepts

When you add an external hypervisor you should be aware (and configure as needed) of:

  • Disks path: By default it will store disks in /opt/isard. That folder doesn't need to be created but it is recommended that speedy IO storage (like nvme disk) is mounted in that path.
  • Network performance: If you are going to use a NAS you should take into account that speedy network must be used. Recommended network speed over 10Gbps.

Disks performance

As different paths are used for bases, templates and groups disks you could improve performance mounting different storage nvme disks in each path:

  • /opt/isard/bases: There will reside the base images you create. Usually those disk images will be used as base for many templates and user disks (groups) so the storage should provide as quick read access as possible.
  • /opt/isard/templates: Templates will also be used as main disks for multiple user disks (groups). So better use a quick read access disk.
  • /opt/isard/groups: Running desktops will reside here. So a lot of concurrent IOs will be done here so the storage should provide as much IOPS as possible. NVME disks (or even NVME raids) will bring the best performance.

Network performance

The storage network between hypervisors and NAS storage servers should be at least 10Gbps. All hypervisors should mount storage in /isard path and that mount should be the same for all hypervisors.

As you can choose when creating hypervisor to be a pure hypervisor, pure disk operations or a mixed one you could add NAS storage servers as pure disk operations. That will bring a quicker disks manipulation as IsardVDI will make use of direct storage and commands on NAS.

We have an IsardVDI infrastructure with six hypervisors and two pacemaker clustered NAS self made that share storage with NFSv4 and the performance is very good.

High Availability / High Performance tech docs

We try to keep all the knowledge and experience of IsardVDI in high performance and availability clusters using pacemaker, drbd, disk caches, live migrations, etc. in the Project Deploy section of the manual.

In that section of the manual there are videos about migrating storage and live virtual desktop that were made on the IsardVDI infrastructure: migrating virtual desktop from one hypervisor to another while at the same time we migrated it's storage from one NAS storage to another without the virtual desktop user knowing what had happened.

Last update: April 20, 2023