Logical Volume Manager Setup and Configuration

Here is a short summary of LVM configuration and setup.

Check to make sure you have LVM2:
vgscan --version

If vgscan complains about missing driver:
modprobe dm_mod

Create physical volumes:
pvcreate /dev/sda1
pvcreate /dev/sda2

Add the physical volumes to a volume group:
vgcreate VolGroup01 /dev/sda1 /dev/sdb1

To create logical volumes out of the volume group:
lvcreate -L <length> -n LogVol01 VolGroup01
ex: lvcreate -L 500M VolGroup01 -n LogVol01
ex: lvcreate -L 20G VolGroup01 -n LogVol01

Create a filesystem
mkfs -t ext3 /dev/VolGroup01/LogVol01

Mount the logical volume
mount /dev/VolGroup01/LogVol01 /mnt/debian

Extending Logical Volume

Unmount the Logical Volume
umount /dev/VolGroup01/LogVol01

If there is free space in the volume group:
lvextend -L +1G /dev/VolGroup01/LogVol01

If the volume group is full then add a disk/partition to it:
vgextend VolGroup01 /dev/sdc1
and then extend the logical volume:
lvextend -L +1G /dev/VolGroup01/LogVol01

Finally, extend the filesystem (any of the below 3 methods)
extendfs -F ext3 /dev/VolGroup01/LogVol01
resize2fs /dev/VolGroup01/LogVol01
resize2fs /dev/VolGroup01/LogVol01 500M

Mount the logical volume
mount /dev/VolGroup01/LogVol01 /mnt/debian

Beginning the new year with Xen

Being the geek that I am, I enter the new year working late with Xen and trying to build an HD file image using the qemu command and watching some early Season 5 episodes of Dexter.

I am just going to document some of my starting out with Xen.

To list all running domains
xm list

To install a new domU from location (online or local)
virt-install --prompt
qemu -hda /dev/domU -cdrom linuxDistro.iso -boot d

Location of domU configuration file on dom0
/etc/xen/nameOfDomU

Start the domU image
xm create -c [nameOfDomU or ID]

Move from domU to dom0
Press: Ctrl-] (control, minus, right bracket)

Connect from dom0 to a running domU
xm console [nameofDomU or ID]

Reboot and Shutdown
xm reboot nameOfDomU
xm shutdown nameOfDomU



The Book of Xen does not have instructions on how to install Xen on a pre-installed system, so the best and most recent guide of installing Xen on CentOS is this one:
Install Xen on CentOS (for 32 bit systems)
Install Xen on CentOS (for 64 bit systems)

They are very similar.

I did create a new CentOS VM to be used as Xen hypervisor. Here are a couple of things I had forgotten:
CentOS time servers are busted, and base install of CentOS doesn't install ntpd.

Initial Configuration

• yum install ntp
• Edit /etc/ntp.conf (change the servers to ones that work)
• Edit /etc/sysconfig/ntpd (enable option to sync the hardware clock)
• ntpdate pool.ntp.org
• chkconfig ntpd on (add ntpd to run when system starts)
• service ntpd start

Setting hostname on CentOS 5.5:

• Edit /etc/sysconfig/network
• Edit /etc/hosts