Lik`s forum

http://wiki.debian.org/Xen

1vm. swapoff
2vm. fdisk /dev/hda -> remove swap partition (comment in fstab)
3dom0. shutdown domU

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xm shutdown vm112

4dom0.

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 lvextend /dev/xennode1/vm112_img -L125G -v

[root@xennode1 ~]# lvextend /dev/xennode1/vm112_img -L125G -v
Finding volume group xennode1
Archiving volume group "xennode1" metadata (seqno 134).
Extending logical volume vm112_img to 125.00 GB
Found volume group "xennode1"
Found volume group "xennode1"
Loading xennode1-vm112_img table (253:1)
Suspending xennode1-vm112_img (253:1) with device flush
Found volume group "xennode1"
Resuming xennode1-vm112_img (253:1)
Creating volume ...

XCP 1.0 is the first full release of the Xen Cloud Platform.
http://www.xen.org/download/xcp/index_1.0.0.html

You can enter into domU using the xm utility:
# xm


Usage: xm <subcommand> [args]

Control, list, and manipulate Xen guest instances.

Common 'xm' commands:

console Attach to <Domain>'s console.
vncviewer Attach to <Domain>'s VNC server.
create Create a domain based on <ConfigFile>.
new Adds a domain to Xend domain management
delete Remove a domain from Xend domain management.
destroy Terminate a domain immediately.
dump-core Dump core for a specific domain.
help Display this message. ...

Xen dom0 not enough free loop devices when trying to start a new domU or when trying to "mount -o loop" from the cmdline

Linux "loop" module has max 8 loop devices (/dev/loop*) as a default. Every Xen "file:" backed domU disk uses one loop device in dom0, and if you do "mount -o loop disk.img /mnt" in dom0 that uses a loop device aswell.

You can check all the loop devices in use by ...

How to install XEN of higher version than 3.3.0 on CentOS5.x

In my case basic OS CentOS 5.4 x86_64 was used.
Browse to http://www.gitco.de/repo/ and grab the needed repo file for your arch and put it into /etc/yum.repos.d. (in this case x86_64).

In case a repo file you need doesn't exist but the folder with this version exists on this repository, then you may simply download any of repo files and change its entry.
Suppose ...

Xen kernel module on each virtual machine (domU) need to be updated to match kernel version on the underlying server (dom0).

Error will be shown in your virtual machine when it is not matched, such as in your iptables, e.g.:

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# iptables -L

iptables v1.3.5: can't initialize iptables table `filter': iptables who? (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.

To resolve the issue and install the missed kernel ...

http://www.fsarchiver.org/Main_Page

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wget "http://downloads.sourceforge.net/project/fsarchiver/fsarchiver-bin/0.6.12/fsarchiver-bin-0.6.12.tar.gz"

In computer networking, TUN and TAP are virtual network kernel drivers. They implement network devices that are supported entirely in software, which is different from ordinary network devices that are backed up by hardware network adapters.

TAP (as in network tap) simulates an Ethernet device and it operates with layer 2 packets such as Ethernet frames. TUN (as in network TUNnel) simulates a network layer device and it operates with layer 3 packets such as ...