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Test: does the  xen list  command show that the current system is Domain-0?

Toolstacks (a.k.a toolkits and toolboxes)

There are several toolstacks available for the personal or scripted administration of Xen resources.

...

Storage

The recommended way to provide storage for a DomU is by an LVM on Dom0 which the DomU uses as a virtual HDD.

Reference: http://wiki.xenxenproject.org/wiki/ChoiceStorage_of_Toolstacks

Apparently, once a toolstack has been chosen, it is not easy to change.  From Debian 7 Wheezy's /etc/default/xen (where the chosen toolstack is configured):

# Attention: You need to reboot after changing this!

libvirt and virsh

libvirt is a library for managing KVM, OpenVZ, VMware, VirtualBox, Xen and others.  For Xen, it is the least feature-complete of all the toolstacks.

virsh is a user/script shell to interface with libvirt.  References: http://libvirt.org/virshcmdref.html

xapi and xe

The most feature-complete of all the toolstacks.

xend and xm

Deprecated since Xen 4.1 but the default in Xen 4.1 as packaged for Debian.  Will be removed from Xen 4.2.

xend comprises:

  • xm command

  • xend-config.sxp config file format

  • xmdomain.cfg config file format

xend was abandoned because of @@@

xl

Strategic since Xen 4.1.

Designed to be command line compatible with xend.  TODO: does it have an xm command?

On Debian 7 Wheezy:

root@SON-OF-blav.bluelightav:~# type xl
xl is /usr/sbin/xl
root@SON-OF-blav.bluelightav:~# ll /usr/sbin/xl
lrwxrwxrwx 1 root root 43 May 5 2013 /usr/sbin/xl -> ../lib/xen-common/bin/xen-toolstack-wrapper

Toolstack library

Libxenlight (libxl)

The strategic Xen toolstack library, designed to hide xenstore, libxenctrl, and libxenguest from higher levels.

Toolstack configuration

Debian 7 Wheezy

The Xen toolstack on Debian 7 Wheezy is configurable.

On blav2, we had explicitly configured using xl:

root@SON-OF-blav.bluelightav:~# diff /etc/default/xen{.org,}
7c7 < TOOLSTACK=
--- > TOOLSTACK=xl

When root runs command xl:

...

options

Networking

Choice:

  • Bridged  Each DomU* OS is connected to the LAN
  • Routed  Dom0 is a router between the LAN and the DomU* network interfaces
  • NATted  Dom0 is a NATting router between the LAN and the DomU* network interfaces

Interface names:

  • peth*
  • vif*
  • veth*
  • xenbr0

Toolstacks (a.k.a toolkits and toolboxes)

There are several toolstacks available for the personal or scripted administration of Xen resources.

Primary reference: http://wiki.xen.org/wiki/Choice_of_Toolstacks

Apparently, once a toolstack has been chosen, it is not easy to change.  From Debian 7 Wheezy's /etc/default/xen (where the chosen toolstack is configured):

# Attention: You need to reboot after changing this!

libvirt and virsh

libvirt is a library for managing KVM, OpenVZ, VMware, VirtualBox, Xen and others.  For Xen, it is the least feature-complete of all the toolstacks.

virsh is a user/script shell to interface with libvirt.  References: http://libvirt.org/virshcmdref.html

xapi and xe

The most feature-complete of all the toolstacks.

xend and xm

Deprecated since Xen 4.1 but the default in Xen 4.1 as packaged for Debian.  Will be removed from Xen 4.2.

xend comprises:

  • xm command

  • xend-config.sxp config file format

  • xmdomain.cfg config file format

xl

Strategic since Xen 4.1.

Designed to be command line compatible with xend.  TODO: what does this mean?  man -k xend lists the config file format xend-config.sxp.  It may mean command line compatible with xm; many of the xl commands take similar arguments to xm.

Unlike xm, xl does not do dom0 network configuration; standard OS tools must be used.

In case there is no local xl man page: http://xenbits.xen.org/docs/unstable/man/xl.1.html and (Xen 4.2) http://manpages.ubuntu.com/manpages/raring/en/man1/xl.1.html

Toolstack library

Libxenlight (libxl)

The strategic Xen toolstack library, designed to hide xenstore, libxenctrl, and libxenguest from higher levels.

Toolstack configuration

Debian 7 Wheezy

The Xen toolstack on Debian 7 Wheezy is configurable.

On blav2, we had explicitly configured using xl:

root@SON-OF-blav.bluelightav:~# diff /etc/default/xen{.org,}
7c7 < TOOLSTACK=
--- > TOOLSTACK=xl

When root runs command xl:

  1. The shell runs /usr/sbin/xl which is a symlink to /usr/lib/xen-common/bin/xen-version to set VERSION to 4.1-toolstack-wrapper
  2. /usr/lib/xen-common/bin/xen-version gets Xen version info from /sys/hypervisor/version/*Sets PATH toolstack-wrapper:
    The shell runs
    1. Sources /usr/lib/xen-common/bin/xen-toolstack to set TOOLSTACK to /usr/lib/xen-4.1/bin/xl
    2. Sources /etc/default/usr/lib/xen-common/bin/xen-dir to set TOOLSTACK to xl (would fall back to hardcoded default otherwise)Sets TOOLSTACK to dir to /usr/lib/xen-4.1/bin/xlexecs
    3. Sources /usr/lib/xen-4common/bin/xen-version to set VERSION to 4.1/bin/xl

      When root runs command xm (does not work):

          1. /usr
        /sbin
          1. /
        xm which is a symlink to /usr/
          1. lib/xen-common/bin/xen-
        toolstack-wrapper/usr/lib/xen-common/bin/xen-toolstack-wrapper:
        1. Sources
          1. version gets Xen version info from /sys/hypervisor/version/*
        2. Sets PATH to /usr/lib/xen-common4.1/bin
        3. Sources /etc/default/xen -toolstack to set TOOLSTACK to xl (would fall back to hardcoded default otherwise)
        4. Sets TOOLSTACK to /usr/lib/xen-4.1/bin/xlSources
        5. execs /usr/lib/xen-common/bin/xen-dir to set dir 4.1/bin/xl

      When root runs command xm (does not work):

      1. The shell runs /usr/sbin/xm which is a symlink to /usr/lib/xen-common/bin/xen-toolstack-4.1wrapper
      2. Sources /usr/lib/xen-common/bin/xen-version to set VERSION to 4.1-toolstack-wrapper:
        1. Sources /usr/lib/xen-common/bin/xen-version gets Xen version info from /sys/hypervisor/version/*Sets PATH to /toolstack to set TOOLSTACK to /usr/lib/xen-4.1/bin/xl
        2. Sources /etc/defaultusr/lib/xen-common/bin/xen-dir to set TOOLSTACK to xl (would fall back to hardcoded default otherwise)Sets TOOLSTACK to dir to /usr/lib/xen-4.1
        3. Sources /bin/xlGenerates usr/lib/xen-common/bin/xen-version to set VERSION to 4.1
          1. /usr/lib/xen-common/bin/xen-version gets Xen version info from /sys/hypervisor/version/*
        4. Sets PATH to /usr/lib/xen-4.1/bin
        5. Sources /etc/default/xen to set TOOLSTACK to xl (would fall back to hardcoded default otherwise)
        6. Sets TOOLSTACK to /usr/lib/xen-4.1/bin/xl
        7. Generates message "ERROR: A different toolstack (xl) have been selected!"

      Configuration

      DomU*

      Networking

      Choice:

      • Bridged  Each DomU* OS is connected to the LAN
      • Routed  Dom0 is a router between the LAN and the DomU* network interfaces
      • NATted  Dom0 is a NATting router between the LAN and the DomU* network interfaces

       

      Installation (domu*)

      ...

      Creating DomUs

      xen-create-image

      xen-create-image is part of the xen-tools package.  TODO: does it build the image from Dom0's OS?  If so we might prefer not to use it because Dom0 was installed from the Hetzner Debian image and an uncustomised Debian may be preferable.

      Using Debian Installer

      Allows installation of an uncustomised Debian.

      Reference: http://wiki.xenproject.org/wiki/Debian_Guest_Installation_Using_Debian_Installer

      Troubleshooting

      TODO: integrate the next para.

      ...

      xen-linux-system-3.2.0-4-amd64

      Documentation only.  TODO: presumably its dependencies are crucial; list them?

      xen-linux-system-amd64

      Documentation only.  TODO: presumably its dependencies are crucial; list them?

      xen-system-amd64

      ...

      Documentation only.  TODO: presumably its dependencies are crucial; list them?

      xen-tools

      Tools that work with the xm and xl toolstacks to administer Xen config files and images.

      ...

      Plus, presumably in suppport:

      • /etc/xen-tools/*
      • /usr/lib/xen-tools/<OS name>.d/*/xen-tools/<OS name>.d/*

      xen-create-image largely automates creating domUs.  Config file: /etc/xen-tools/xen-tools.conf.  The --lvm option creates a new logical volume which is available to the domU as a hard disk drive

      Logs in the /var/log/xen-tools/ directory.

      ...

      xen-utils-4.1

      Tools to control the hypervisor from dom0.

      Provides (in /usr/lib/xen-4.1/bin/):

      ...

      peth*