在Debian Etch上安装使用OpenVZ

Introduction

Virtualization is nice! A good practice for servers, since it makes things more secure, scalable, replacable, and replicable. All this at the cost of little added complexity.

This guide is written during an install of a Supermicro machine with 2 dual-core opterons (64-bit), 2 identical disks (for RAID) and a load of memory. Why OpenVZ and not XEN or the recent KVM kernel module? Well, XEN is not very stable for 64-bit architectures (yet), and it comes with quite a bit of overhead (every VM runs its own kernel) due to its complexity. KVM is very simple but restricts you to run a kernel as one process, so the VM cannot benefit from multi core systems.

With OpenVZ only one kernel is run for the host environment _and_ all the VMs, this makes the setup lean and a good candidate for webservers.

Install the hosting system

First install Etch (make sure to set up RAID with the installer).

You might want to rid yourself of some cluttering directories and links in your root (and, as the rest of the guide, as root):

cd /
rm cdrom
unlink vmlinuz.old
unlink vmlinuz
rmdir selinux/
rmdir initrd
unlink initrd.img.old
rmdir opt
rmdir srv/

Now we want to compile a custom OpenVZ enabled kernel, we kind-of followed this guide on the OpenVZ site. A short overview of what we did:

apt-get update
apt-get install linux-source-2.6.18 kernel-patch-openvz vzctl vzquota # this command might need you to acknoledge
cd /usr/src
tar xjvf linux-source-2.6.18.tar.bz2
cd linux-source-2.6.18
cp /boot/config-2.6.18-3-amd64 .config
aptitude install kernel-package # you need it in the next line
make-kpkg --append_to_version=-1-openvz --added_patches=openvz --revision=1 kernel_image
cd ..
dpkg -i linux-image-2.6.18-1-openvz_1_amd64.deb
update-initramfs -c -k 2.6.18-1-openvz
update-grub

Then (after you might have modified the /boot/grub/menu.lst a bit to default to the right kernel) you can reboot.

After the reboot using the OpenVZ enbabled kernel check if all works:

ifconfig # should list your interfaces and an additional "venet" inteface
cat /proc/vz/* # should show somethings (not very important yet what it shows)
cat /proc/cpuinfo # se that your CPUs are up
cat /proc/mdstat # RAIDs working
lsmod # should show some modules starting with the letters "vz"

Make Virtual Private Servers (VPSs)

No we setup, start a VPS from the default minimal template (you can find it in /var/lib/vz/template/cache):

vzctl create 101 --ostemplate debian-3.1-amd64-minimal --config vps.basic
vzctl set 101 --onboot yes --save
vzctl set 101 --hostname test101.mytest.org --save
vzctl set 101 --ipadd 10.0.0.101 --save
vzctl set 101 --numothersock 120 --save
vzctl set 101 --nameserver 10.0.0.2 --save
vzctl set 101 --privvmpages 500000:750000 --save # give it some memory CHECKME
vzctl start 101
vzctl exec 101 passwd

Then you can connect with the VPS by

ssh 10.0.0.101

, and note the colorful prompt...

This template is a Sarge (3.1) template, and I want it to be Etch (4.0), so when logged in to the VPS as root do:

nano /etc/apt/sources.list # edit it to match the sources.list on you host (Etch) install
aptitude update
aptitude dist-upgrade

Now try out your new VPS, and make it workable, install the packages you like to have around since this systems will later serve as basis for further VPSes.

Next we creating a template from the just customized VPS, this is an easy thing:

vzctl stop 101 # stop it
rm -f /var/lib/vz/private/101/etc/ssh/ssh_host_* # remove the keys (new ones will be generated on first boot)
cd /var/lib/vz/private/101/
tar czf /var/lib/vz/template/cache/debian-etch-20061218-amd64.tar.gz .

As Borat would say: "Nice! I like!"

No we can setup and run some additional VPSs, as before but now slightly modified:

vzctl create 102 --ostemplate debian-etch-20061218-amd64 --config vps.basic
vzctl set 102 --onboot yes --save
vzctl set 102 --hostname test102.mytest.org --save
vzctl set 102 --ipadd 10.0.0.102 --save
vzctl set 102 --numothersock 120 --save
vzctl set 102 --nameserver 10.0.0.2 --save