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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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Why do we use a OS Base Image with Docker if containers have no Guest OS?

I've just started to study Docker and there's something that's being quite confusing for me. As I've read on Docker's website a container is different from a virtual machine. As I understood a container is just a sandbox inside of which an entire…
user1620696
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Is it possible to make Nginx listen to different ports?

I created one Nginx with one Linux Azure VM, is it possible to make nginx listen to different ports so that when I change the port number, the content would be different. I found there would be a collision if I created two or more ports related to…
billcyz
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What range of MAC addresses can I safely use for my virtual machines?

I want to assign my virtual machines MAC addresses so that I can configure DHCP reservations for them so that they always get the same IP address regardless of which host hypervisor they are running on or operating system they are running. What I…
Chris Magnuson
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How do I know if I'm working on a Virtual Machine or not?

Is there a way to know if the Windows machine I'm working on is virtual or physical? (I'm connecting with RDP to the machine. If it's a virtual machine it is working and handled by VMWare).
user33705
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Is a VM with 2 CPUs really faster than one with 4 CPUs?

Our IT created a VM with 2 CPUs allocated rather than the 4 I requested. Their reason is that the VM performs better with 2 CPUs rather than 4 (according to them). The rationale is that the VM hypervisor (VMWare in this case) waits for all the…
AngryHacker
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Creating a virtual machine in VirtualBox from a physical one

Is there any way to create a virtual machine that you can use in VirtualBox from a physical installation that you have? For instance, if I have Windows XP installed on a physical computer and want to have a virtual version of that machine on a…
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Is it possible to setup a virtual machine inside another virtual machine

I've been playing with virtual machines lately, and I wondered if I could run a virtual machine inside a virtual machine. Is this possible? Is it practical?
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Why VM snapshots are affecting performance?

I read in one of the VMware KB articles that snapshots will directly affect VM performance. But my team keeps asking me how snapshots can affect performance. I would like to give them solid reason behind the statement the snapshots are performance…
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Will virtualizing a server mean another OS layer to patch and update, more work and greater risk?

I've done a search and have not found anything addressing issues regarding patching and system updates. I've got guidelines that say servers need to have necessary patches. If I have a VM host then is that an extra layer to patch and update - even…
user127379
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KVM and Libvirt - How do I hotplug a new virtio disk?

I am trying to hot-add a file-based disk to a running KVM virtual server. I've created a new disk from scratch using the command dd of=/home/cloud/vps_59/test.img bs=1 seek=5G count=0 and I was hoping to get it hot-added to the guest by doing this…
Daniele Testa
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Is there a reason to give a VM a round base-2 amount (2048MB, 4096MB, etc) of memory?

The title pretty much says it all, is there any advantage to giving a VM 2048MB of memory instead of rounding to base-10 and doing 2000MB?
Nate
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When shall I use linked vs full VM clones?

I've seen documentation for the Full and Linked virtual machine clones, but I can't seem to fully understand when I should use one over another. I see that the full clone creates a copy of the VM, but what about the linked one -- does it mean…
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Running 100 virtual machines on a single VMWare host server

I've been using VMWare for many years, running dozens of production servers with very few issues. But I never tried hosting more than 20 VMs on a single physical host. Here is the idea: A stripped down version of Windows XP can live with 512MB of…
Dennis Kashkin
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Why Are There Only 65,535 Ports, and Will We Ever Have More?

I understand the original reasoning behind having 65,535 ports per IP address: this is the highest number that can be represented by a 16-bit, or 2-byte, number, and it wasn't conceivable that computers would ever be able to spare more than that for…
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Sync LVM snapshots to backup server

I have a number of Xen virtual machines running on a number of Linux servers. These VMs store their disk images in Linux LVM volumes with device names along the lines of /dev/xenVG/SERVER001OS and so on. I'd like to take regular backups of those…
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