300+ [REAL TIME] OpenVZ Interview Questions

1. How Openvz Different From Other Virtualization Technologies?

• OpenVZ is not flexible to provide the services that are being provided by other virtualization platforms.
• OpenVZ is partial virtualization and act as a containerization, whereas other virtualization technologies are either type1 or type2 Hypervisors.
• OpenVZ uses kernel patches to run only Linux operating system, whereas other virtualization platforms can run more than one operating systems. 
• OpenVZ is fast and efficient compared to other virtualization technologies.

2. What Is The Main Function And Use Of Openvz?

OpenVZ is also known as Open virtualization is an operating system level platform that is based on Linux kernel and can run system that is based on Linux architecture. It can run multiple Linux system instances in what is called as containers. It contains Linux base operating system and gives very high performance compared to standalone servers. OpenVZ is free to use and imply. It provides custom level kernel to provide the support for its containers and user level tools.

3. What Are The Containers That Are Involved In Virtualization And Isolation?

The container consists of:

• Files that consist of system libraries and applications that provides programmers to write the code without looking further. It provides virtualized files as well that keeps the virtualization for the user. 
• Users and groups: it consists of isolated root user that allow user to group other users and set the permissions individually or either as groups. 
• Process tree: consists of processes that contain other processes under it. The level start from init and it goes as the each process is added. 
• Network: consists of the configuration for virtual network devices and the entire container to have its own IP addresses for communication with other devices. 
• Devices: consists of access permissions that are used to connect it with the real devices like network interfaces, serial ports, parallel ports, etc.
• IPC objects: consists of the files that are used for inter process communication like shared memory, semaphore, etc

4. What Are The Different Features Of Openvz?

OpenVZ is a operating system level virtualization platform and provides features like:

• Scalability: this consists of configuration related to hardware like CPU, RAM etc. 
• Performance: this consists of performance related issues that are very few in OpenVZ and it reduces the overhead that is being associated with other virtualization platforms
• Density: provides the decrease of overhead that is required by the container and doesn’t allow the demands to exceed the physical availability of the resources.
• Mass management: provides administrator rights to use the physical server of OpenVZ so that user can see all the processes that are running on the system and the containers that are consisting inside the OpenVZ

5. What Are The Required Steps To Improve The Efficiency Of Services In Openvz?

OpenVZ utilizes the processing power to reduce the overhead by decreasing the load that is given on a system. It provides better methods to improve the handling of peak loads. It also reduces the complexity by providing standardized and centralized management of the server from one place. It provides a way to isolate the servers from the actual hardware. It uses high-end servers by isolating the server from hardware and with the servers bring added advantages like reliability, longer lifespan, etc.

6. How To Setup The Tun/tap Network For A Container?

OpenVZ uses tun/tap network module to configure a container. To setup the container using tun/tap device: 

• Check your system and see that tun/tap module is already being installed. Use the command to find out:

  |smod| grep tun

•  If not present then use the command to load the tun module:

  modprobe tun

• Edit the modules.conf that is inside /etc/ to allow the tun module to run automatically during the start of the system. 
• Set the permission for the container to use the tun/tap module
• The following command allows the container to be set with the permission for the use of tun/tap networking module:

  vzctl set 101 –devnodes net/tun:rw –save

7. What Are The Commands That Are Required To Manage Openvz Virtual Machine?

The commands that are required to manage OpenVZ are as follows:

To show a list of all running VPSs we require a command named vzlist that list the containers and its parameters.The command that is used with it is:

vzlist -a

The commands can have many parameters like -o that displays only specified parameters with the name.

To calculate the usage for each container’s resources a command named vzcalc is used that show all the shared host system resources that is used by a particular container.-v is the parameter that is used to show only the valid containers that are currently in use.

8. How To Over-commit The Memory In Openvz?

To over-commit the memory in OpenVZ few pages has to be modified like vmguarpages and oomguarpages that provides the resource management configuration files. Out of these vmguarpages provides the maxium memory a container can have and oomguarpages provides the maximum memory that is being consumed by the processes. These are used to set the limit. Limit also has some files like privvmpages that puts an upper limit on container memory. It is also used for non-swappable kernel memory. By using these functions over-commitment of the memory can be done by using OpenVZ.

9. What Is The Function Of Veth In Openvz?

Veth stands for virtual ethernet device and it is used as an ethernet device in OpenVZ. It is used inside a container and veth consists of MAC address. Veth uses bridged connection configurations with other devices to setup the networking between the two parties for the communication. It includes IPs and gateways to successfully setup the networking interface. This ethernet device contains two ports one is called as CT0 and another is CT. they are connected with each other and they work as interconnected device such that one’s input is another’s output.

10. What Is The Use Of Virtual Environment In Virtuozzo?

Virtuozzo is an operating system that provides virtualization platform just like any other virtualization platform. It works well with the OpenVZ. It has it own containers that has the functionalities to provide the user with easiness and provide the environment in which management tools, recovery, etc can be incorporated. It provides the automation solution and built on top of OpenVZ.

11. What Are The Benefits Of Using Virtuozzo?

The benefits of using virtuozzo are as follows:

• Higher container density: It provides better performance of the containers used in the systems and increases the memory and file sharing rate between the shared systems.
• Memory management: It is easier to manage memory segments using this as it provides lots of easy to use tools for managing the memory module.
• Management tools: It allows user to monitor, troubleshoot and administer their own virtual machines to manage the memory and other resources.
• Support and maintenance: There are lots of tools and support provided for recovery and other back up tools.

12. How To Use And Maintain Virtuozzo?

Virtuozzo is a simple operating system to be used and managed. It allows the user to customize the platform using the built in management tools. It provides consistency between different platforms that are used. It maintains the tasks of different operating system together for easy maintenance and sharing. There are management tools that allow user to patch their product and if any difficulty can just upgrade the software version.

13. What Is The Use Of Physical To Virtual Tool For Linux In Virtuozzo?

Physical to virtual tool for Linux is used while deploying virtuozzo. It is used a migration tool between physical and virtual machines. This makes it easy for the operating system to deploy all the necessary services and applications that are required by the operating system. It allows the testing processes to be migrated to ensure the performance and efficiency levels.

14. What Is The Density Level Achieved By Virtuozzo?

The density range talks about the resources of the server, content of the server and the virtual environment in which all the things are taking place. The two most important resources that are required by any virtualization platforms are CPU and RAM. The more the processing power the fewer requirements will be for the offload processing. Virtuozzo achieves a high density for example of 100 virtual environments as it has minimal content and applications when used with Linux operating system but when used with windows more resources is being taken up by windows operating system.

15. What Is The Overhead That Comes While Using Virtuozzo?

Virtuozzo allows one server that is dedicated to be split into multiple virtual servers and called as virtual environments. It doesn’t add high amount of overhead but it keeps to minimal, as it adds only the native applications and operating system. It increases the performance by decreasing the overhead.

16. What Is The Difference Between Virtuozzo And Esx Server?

• Virtuozzo containers produce the virtualization at operating system level so they are called as type-2 Hypervisors, whereas ESX server produce the virtualization at hardware level and they are called as type-1 Hypervisors. 
• Virtuozzo provides low overhead compared to ESX server due to hardware level configurations.
• Virtuozzo provides high performance and high resources at lower cost compared to ESX server. 
• Virtuozzo’s containers provide the virtualization at the same level and there is no need for hardware virtualization, whereas ESX server has to be configured at the hardware level to produce the resources.

17. What Are The Disadvantages Of Using Virtuozzo?

The disadvantages of using virtuozzo are as follows:

• Flexibility: Fexibility decreases due to operating system virtualization as all the containers uses the same operating system.
• Virtuozzo containers can’t use different operating system and have different configurations. 
• It can’t virtualize the systems at high scale as it will require more resources.
• It can’t run high end operating system or else there is a degrade in the performance of the systems. 
• The connectivity of the system is such that it can communicate only in a small range and doesn’t have very high-end tool to manage the changes.

18. How To Manage Virtual Networks?

Virtual networks allow the creation and management of one or more virtual machines. It binds the container’s virtual network adapter with the physical adapter that is associated with the network. It allows user to create virtual network on hardware node, remove an existing virtual network, and list all the networks that are present with their properties and configurations.

19. How To Enable Nat For Virtuozzo Container?

To enable the NAT services for virtuozzo container multiple servers has to be connected with the internet using the single IP address. The containers are running in host and bridged mode. NAT allows user to access the resources that are present on the internet. The command and properties combination that can be used to set the NAT for the container is

vzctl set 101 –nat on –save

This command will set the NAT for any container on the node. The 101 that is used is for a container that enables NAT for default virtual network adapter.

20. What Is Openvz And How It Compares To Virtuozzo?[

OpenVZ is a free and opensource portion of Virtuozzo. It includes core of Virtuozzo functionality, like kernel and command line management tools for creating and managing containers. Virtuozzo includes everything that OpenVZ does, plus additional features and services available with the commercial version only.

21. How Does Virtuozzo 7/openvz Pair Compares To Its Predecessor (virtuozzo Versions 4.x And 6/openvz)?

Previously, OpenVZ and Virtuozzo were built out of the same code base with some unique patches applied. That warranted the user interfaces to be similar but not identical. With Virtuozzo 7, the compatibility will be on the binary level – effectively the open source components will be the same between OpenVZ and Virtuozzo.

22. How Openvz Users Will Benefit From It?

OpenVZ components will be undergoing the same testing procedures as the commercial product. Also, some new features previously available on Virtuozzo only (notably hypervisor) will become available on the product built for OpenVZ community users.

23. What Support Options Are Available For Virtuozzo 7?

For the moment, only preview (beta) versions of Virtuozzo 7 are available. They are intended for development and testing only, not for production. Virtuozzo 7 is not yet commercially supported. For supported commercial version, please refer to Virtuozzo 6.

24. When Openvz Will Be In Upstream Kernel?

Our kernel developers work hard to merge containers functionality into the upstream Linux kernel, making OpenVZ team the biggest contributor to Linux Containers (LXC) kernel, with features such as PID and network namespaces, memory controller, checkpoint-restore and much more.

25. How Scalable Is Openvz?

OpenVZ technology scales as well as standard Linux kernel — up to thousands of CPUs and terabytes of RAM.

26. How To Install Openvz?

There are two versions of OpenVZ available:

• stable version: OpenVZ legacy (based on RHEL5 and RHEL6 kernels).
• development version: Virtuozzo Linux distribution based on RHEL7 kernel.

27. How Existing Openvz Users Can Upgrade To The New Version?

While there is no in-place upgrade, we prepared upgrade script for OpenVZ users to move their containers to the new platform. The script allows to transfer containers from old to new OpenVZ version (or from OpenVZ to Virtuozzo).