FAQ

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Revision as of 00:20, 11 August 2009 by Tallpeak (talk | contribs) (How can I assign a physical disk to a VM?)
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tbd, if possible, detailed answers should linked to internal wiki pages

General

What is a container, VE, Virtual Private Server, VPS?

See Container and Full Virtualization

What is a KVM guest (KVM VM)?

A KVM guest or KVM VM is a guest system running virtualized under Proxmox VE with KVM.

What is a Virtual Appliance?

See Overview

Installation and upgrade

Where can I find installation instructions?

See Installation

Networking

Troubleshooting

I can't switch virtual consoles in Linux KVM guests with alt-F1, alt-F2...

VNC viewer does not pass some key combinations or they may be intercepted by your operating system.

To send custom key combinations to the guest, go to "Monitor" in Virtual Machine Configuration for a given guest and use "sendkey" command.

For example, to switch to the third console (tty3) you would use:

sendkey alt-f3


How can I send sysrq to Linux KVM guests?

Similarly to the above, go to "Monitor" in Virtual Machine Configuration for a given guest and use "sendkey" command.

For example, to issue "Emergency Sync", you would use:

sendkey alt-sysrq-s

In the VNC viewer for the given guest you should see:

SysRq : Emergency Sync

You should also see this entry if you run "dmesg" on this guest.

See also http://en.wikipedia.org/wiki/Magic_SysRq_key for a full reference of possible combinations.


How can I access Linux guests through a serial console?

Sometimes, it is necessary to access the guest through a serial console:

  • you lost network access to the guest and VNC is either too slow for you or don't have the features you need (i.e. easy copy/paste between other terminals)
  • your guest freezes or kernel panics, you want to debug it, but it's impossible to capture all messages on VNC screen
  • you are familiar with xm console <guest> from Xen and you want to use a similar feature here


The necessary steps are:

  • on Proxmox VE host, in guest's configuration file in /etc/qemu-server/<VMID>.conf add:
args: -serial unix:/var/run/qemu-server/<VMID>.serial,server,nowait

This will open console in /var/run/qemu-server/<VMID>.serial socket file, which can be accessed by minicom or other serial communication program.

An alternative is to add:

args: -serial tcp:localhost:6000,server,nowait

With this, you can connect to guest's serial console with telnet. Note that with telnet, any passwords will be visible on the screen.


  • on guest, in /etc/inittab, look for lines similar to the ones below and make sure you have "ttyS0" there - this would be your serial console:
5:2345:respawn:/sbin/mingetty tty5
6:2345:respawn:/sbin/mingetty ttyS0

If you want kernel messages to be shown on both serial and VGA consoles, you have to add a kernel parameter in your bootloader's configuration. For grub, it would be these "console" entries:

kernel (hd0,0)/boot/vmlinuz root=LABEL=guest-root console=ttyS0 console=tty0


To access the guest from minicom, configure it to use a path such as unix#/var/run/qemu-server/<VMID>.serial in "cOnfigure Minicom -> Serial port setup -> Serial Device".


To use multiple minicom configurations for several guests, create a file like /etc/minicom/minirc.someguest for each of your guests, with contents:

pu port             unix#/var/run/qemu-server/<VMID>.serial
pu minit
pu mreset


Then, start the console with:

minicom someguest


See also http://www.proxmox.com/forum/showthread.php?p=5615

How can I assign a physical disk to a VM?

Add it first in the web interface, then use:

qm set <vmid> -ide# /dev/sdb

Or:

qm set <vmid> -ide# /dev/disk/by-id/[your disk ID]

...since having the drive letter change (should you add a drive) might have unintended consequences.

Also see /etc/qemu-server/<vmid>.conf