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Stratus.FI is a software-based private cloud for FI users OpenNebula .

The primary purpose is to provide users with an environment for experimentation and quick testing or even production use of software that, for various reasons, cannot be installed directly on servers managed by CVT FI (such as Anxur or Aisa).



The Stratus.FI cloud web interface can be found at the following URL:

Log in to the web interface with the faculty login and faculty password (more about the faculty account and password change here ).

Cloud versus User view

The Stratus.FI web interface is available to users in two versions: a simpler cloud view , which is set by default and which is described in chapter I want to quickly create a virtual machine , and a more complex user view with left menus and more controls. You can switch between them by clicking on the username and selecting the last item named Views . Compare - cloud view:

Cloud view

... a user view:

User view

User context configuration

Pre-installed images of virtual machines are configured to take some information from user settings (SSH key, superuser password, ...). Therefore, you must set these parameters before you can create a virtual machine. Sign in to web interface , click on the username at the top right and select Settings from the menu:

ssh key

SSH key

If you don't have one yet, create an SSH key for example on Aise with the command:

ssh-keygen -b 4096 -t rsa

The secret key will be saved to a file $HOME/.ssh/id_rsa and public there to file . When creating, you can enter a password ( passphrase ), which will be required each time the SSH key is used.

In the web interface in the user settings, click on the Config section and then on the Add SSH Key item, and copy the public key - file content to the form window .


Encrypted password

Create an encrypted password for the virtual machine, for example, with the command openssl passwd -1 on Aise or other Linux:

openssl passwd -1

correct horse battery staple
Retype password: 
correct horse battery staple

In the user settings in the Stratus.FI web interface (must be in user view ) add a new attribute named at the very bottom of the Attributes section CRYPTED_PASSWORD , the value created above (string $1$... ) and save by clicking on [+] .

Password for Windows VM

To use a Windows virtual machine, you must enter the user attributes (must be in user view ) add two additional attributes: WIN_USERNAME with username and WIN_PASSWORD containing an unencrypted login password. Here we recommend choosing a different password than you use on faculty systems.

Choose a non-trivial password, otherwise Windows may refuse to log in to the VM with a password that is too simple.

Overall, the set context information looks something like this:


I want a pre-installed virtual machine

Use the following procedure if you need to try something on a pre-installed machine (run / compile your version of some software, etc.) and you do not want to waste time installing and configuring the operating system.

Configure the user context as described in the previous chapter .

Open up main page Stratus.FI (from another Stratus.FI site, click on the Dashboard at the top).

Click green on the left side of the page [+] .

Choose from a menu of pre - installed systems (for example CentOS 8 , Fedora or Debian 10 ) and click on the selected system.

Note the templates that have the name [CVTFI] , are templates created by us, are intended for users, and should have contextualization packages installed, that is, they should have a working network and it should be possible to log in to them with a password and SSH key from the user's context. Therefore, if you encounter a problem with a template marked this way, do not hesitate to contact us and we will try to resolve it with you.

Note: If it is production virtual machine, select the persistent option (for more see creating disks ). We also strongly recommend using a distribution with long support (eg CentOS or Debian).

Fill in the name of the created virtual machine on the left side of the page (for example, Test CentOS ) and click on the green Create on the right.

Wait until the name of the just created virtual machine has a green square instead of an orange one (you can restore the view with the icon of the two arrows in the circle shown at the top right).

Once the virtual machine is active, you can from the internal FI network (for example, Aisa, Anxura, Wi-Fi or VPN ; see also access to the FI network ) for example, try logging in via SSH to the IP address displayed on the created virtual machine (if the template uses SSH contextualization, it has an SSH server and an IP address). You can get to the machine console by clicking on its title and then on the bottom left of the blue terminal icon. You can log in as root with a previously entered password.

For newly instantiated machines, we recommend updating the packages, especially if you plan to use the machine for a longer period of time and restart the machine for their full application.

Newly created virtual machines are assigned a NATed private IPv4 and a public IPv6 address. It is no longer necessary to use the HTTP proxy cache to access the public IPv4 Internet. You can read more about the technical solution in our blog in IS.

If you want to use such a virtual machine more permanently and you need a larger disk, enlargement is possible, but the disk must be connected to the running virtual machine for this operation (it can be enlarged in the Storage tab).

Quotas and rules of use

Our goal is to enable users to use a larger amount of computing resources (up to 10 virtual machines) in the short term . Users will have the opportunity to try out distributed applications, for example. Therefore, system resource quotas are set for this usage. You can find exact information about quotas in the web interface in the user settings in the Quotas section.

Please be considerate of other users: the current hardware does not have the capacity for each FI user to use all resources permanently at the same time up to the size of their quota. Therefore, the set quotas do not apply to running virtual machines . If we detect virtual machines running for more than a day, or a maximum of small units of days, we will terminate these machines and later erase their disks.

If you need a longer-running test, production virtual machine, short-term amount of computing resources, or are considering use of Stratus.FI for teaching , contact your system administrator at .

When using virtual machines, keep in mind that this also applies Operating rules , in particular the ban on the operation of publicly available network services without the prior approval of the head of CVT FI.

VCPU vs CPU: When allocating resources to a virtual machine, two parameters are set, among others: VCPU and CPU . The integer parameter VCPU means how many processors will see the virtual machine, ie how many cores of the host computer it will be able to spread its work. The real CPU parameter is less important - it is used as information about how much computing power this VM will occupy on average in the long run. In short: if you only need a sudden parallel power, set only the VCPU .

I want to install my operating system

In this chapter, we will assume that the user has the interface switched to User view .

Creating disks

For your virtual machine, you will need the installation media (CD-ROM image), the system disk, and possibly a volatile disk for temporary data, such as swap space. To view the available disks, click StorageImages in the left menu.

If you do not find the installation media of your chosen system among the available disks, you can create them:

  • click on the green [+] at the top of the page,
  • fill in the disk name (for example CentOS 7.1511 netinst.iso ), or the description,
  • select Read-only CD-ROM as the type and leave the datastore cephds ,
  • under Image location , select Upload and browse the ISO image on your computer,
  • create an image by clicking on the green Create above.

The newly created disk should appear in the list of available disks. To save disk space, offer the ISO image you have introduced to other users as much as possible: click on the appropriate line in the list of disks and add the Use right for Group and Other in the access rights on the right side of the page.

Similarly, create a system disk. On the StorageImages page, click on the green [+] , fill in the disk name (for example, MyTest ) or the description. Choose Generic storage datablock as the type , leaving cephds storage. Important: check the This image is persistent checkbox . (Non-persistent image: created instances use a copy-on-write copy of this image. When the VM is canceled, the changes made will be lost. Persistent image : can be used by only one VM, the changes made are retained even after the VM is canceled.) image and enter the size. Click the green Create at the top of the page to complete the action. After creating a disk, you can still click on its row in the list of disks and change the disk type from DATABLOCK to OS .

Virtual machine template

Stratus.FI (OpenNebula) uses templates to describe what a virtual machine should look like. Templates are primarily intended for when you need to efficiently create a large number of identical virtual machines, for example for load balancing. However, every virtual machine must have a template, even though we know in advance that it will always run in only one instance.

In the left menu, select TemplatesVMs , which will display a list of available templates (all your own and public ones). Click the green [+] to create a new template. On the General tab, fill in the template name, default memory size, and processor information: the CPU entry determines the complexity of this virtual machine for the purpose of selecting the physical node where the machine will run. Because the machine will probably not take up the entire processor for 100% of the time, set the value to around 0.2 . The VCPU tells you how many processors the virtual machine's operating system will see. Set the value to 1 . Leave Hypervisor on KVM.

Next, click the Storage tab at the top of the page (next to the General tab). Select (leave) the Image type as Disk 0 and select the disk created above from the list. You add another disk with a blue (+) . Select the installation CD-ROM as Disk 1 . Similarly, you can add a Volatile disc , such as a swap . This disk is not a separate image, it is always re-created when the template is instantiated. One of the suitable types of use is storage space. If you are going to install Windows, you may also need to connect Virtio Windows drivers .

On the third Network tab, you set the network interfaces of the virtual machine. Connect the NIC 0 to the 503-usrpriv network.

The fourth OS Booting tab controls the boot order of the disks. To install the operating system from the CD-ROM image, select this image first (check boot from Disk 1 and use the arrows to move this disk above).

You don't have to set anything else on the other tabs at this stage, just click on the green Create at the top of the page.

Start the virtual machine

Based on the created template, we can create ( instantiate ) a virtual machine. Select the appropriate template from the list by clicking on its row, and from the detailed page about the given template, click on the blue Instantiate at the top. Here it is still possible to change some parameters for a specific instance, this is mainly used for customizing pre-installed images and templates. Just click on the green Instantiate at the top of the page.

The newly created virtual machine is visible in the list of virtual machines: InstancesVMs from the left menu. The assigned network addresses are also visible here. When installing a new system, set up the network statically; copy this information to the installer. For production virtual machines, it is better to use context packs that the system sets up itself, for example addon-context-linux , addon-context-windows .

You can access the virtual machine console using the terminal icon on the right in the list of virtual machines, or using the terminal icon with the word VNC from the details page of one virtual machine. Here you can continue with the system installation.

After instalation

After the installation, you only need to turn on disk booting. Shut down the installed virtual machine ( shutdown button at the top of the page with details about this virtual machine, and then Undeploy ). Then select the Conf tab on the far right, click on the green Update Configuration and change the boot order. Click Green Update at the top of the page to save your changes. You can then start the virtual machine with the triangle button to the right ("Play", ). Alternatively, a similar effect can be achieved by completely dropping the virtual machine (the persistent disk remains), modifying the template, and re-instantiating.

Useful configuration

Finally, we recommend checking the list tips when installing the machine on FI . It contains useful advice of both a general nature and advice on how to use some services specific to the faculty network.


Stratus.FI consists of three monitoring (control) nodes and ten guest nodes, which also provide storage via a distributed system Ceph .

To give you an idea, the host nodes have the following parameters:

  • Two thirty-two AMD EPYC 7351 processors operating at 2400 MHz
  • Each core has a 512 KiB L2 cache
  • Each processor has 8 MiB shared L3 cache
  • Two 12TB rotating disks for Ceph
  • They are connected to the network at 10 Gbit / s full-duplex
  • 512 GiB RAM in sixteen 2400MHz modules
  • CentOS operating system version 7