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Questions tagged [virtual-machines]

A virtual machine (VM) is a completely isolated guest operating system installation within a normal host operating system. It is a software implementation of a machine (i.e. a computer) that executes programs like a physical machine.

Modern virtual machines are implemented with either software emulation or hardware virtualization. In most cases, both are implemented together. Usually the term refers to system virtual machines which provide a complete system platform which supports the execution of a complete operating system (OS). Note that process virtual machine exist too, which are designed to run a single program (a single process).

An essential characteristic of a virtual machine is that the software running inside is limited to the resources and abstractions provided by the virtual machine—it cannot break out of its virtual environment.

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Virtualization Pitfalls/Lessons Learned

What are some pitfalls or lessons learned after converting existing hardware to a virtualized environment? Is there anything you tried to virtualize but will never do again?
Bob
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mount.nfs: access denied by server while mounting

On my Ubuntu system, I have this line in /etc/fstab: myserver:/home/me /mnt/me nfs rsize=8192,wsize=8192,timeo=14,intr When I do sudo mount -a I get: mount.nfs: access denied by server while mounting myserver:/home/me How can I diagnose this…
JoelFan
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Is it safe to mount the same partition to multiple VMs?

I'm using ubuntu 20.04 with Xen Hypervisor. On my machine I have an SSD that hosts my VM images, and then four sata drives which I have data on. My current set up is to mount the data on my domain0 and then provide that data to the other VMs over…
curios
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Cloning Virtual Machine On Azure, keeping existing

There doesn't seem to be a straight answer online about this. I have an existing Virtual Machine on Azure and I want to clone it to another region in case my existing server goes down. It needs to be the exact replica but all I can find are moving…
exposure
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How do I get /dev/random to work on an Ubuntu virtual machine?

Apparently, /dev/random is based on hardware interrupts or similar unpredictable aspects of physical hardware. Since virtual machines don't have physical hardware, running cat /dev/random within a virtual machine produces nothing. I'm using Ubuntu…
Nick
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How to attach a virtual hard disk using VBoxManage?

What is the best method for setting the virtual hard drive (VDI) of the primary controller for an existing virtual machine? Does the syntax change if the VDI is really a child differencing disk of some other parent disk? Do you need to attach the…
Adam
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Why do cloud compute instances spin up VMs and not containers?

In AWS for example, when I spin up a new EC2 instance, it loads up a new VM, then populate the VM with a container image. This is the reason why spinning up new EC2 instances take 60-90 seconds to start. Out of curiosity, what are the disadvantages…
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Can a VMWare Server 2.0 virtual machine be "unvirtualized" to physical hardware?

We have a number of VMWare Server 2.0 virtual machines that were created using VMWare Converter (It copies a physical machine to a virtual machine). If we need to convert the virtual machine back to a physical machine is there way to accomplish this…
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understanding relationship between Qemu and KVM

What is the difference between KVM and Qemu? As I understand, latter is able to provide "user mode emulation" which means that one can run a single executable built for some other architecture like this: # file busybox-sparc busybox-sparc: ELF…
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Hyper-V vs. ESXi vs. XenServer

Can anyone share their experiences (for example, this was great! This failed miserably!) with using the Hyper-V, ESXi, and XenServer virtualization platforms? Cost? Management? features? Handling load and backups and recovery? And also minimum…
Bart Silverstrim
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Is there a way to have a virtual machine only have one core yet use three cores on the host machine?

Possible Duplicate: Can a single Virtual Core on a VM use more then 1 physical core? I'm a co-owner of a Minecraft server that is getting rather large each day, but as we get bigger we're running into the limits of Minecraft and the way it's…
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How is memory allocated in ESXi server?

We have an ESXi 4.1 server with 48 GB RAM. For each VM, we are allocating 4GB of memory. Since the server will have 13 virtual machines, my manager thinks this is wrong. I am going to explain to them that ESXi will actually manage memory itself, but…
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So really, what is the overhead of virtualization and when should I be concerned?

I'm searching for good rules of thumb to understand when NOT to virtualize a machine. For example, I know that a fully CPU-bound process with near 100% utilization is probably not a good idea to virtualize, but is there any sense in running…
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PING icmp open socket: Operation not permitted in vserver

I am running a vserver environment with several virtual machines. A single VM has the following problem: $ ping 8.8.8.8 ping: icmp open socket: Operation not permitted $ ls -l $(which ping) -rwsr-xr-x 1 root root 30736 2007-01-31 00:10 /bin/ping $…
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Running containers inside a virtual machine?

It is my understanding that containers are much more lightweight than VMs because they do not virtualize the hardware but instead just isolate the software running in them from software running in other containers on the system. My situation is such…
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