This is based around packages which I maintain for both distributions including a Dom0 kernel for CentOS 6. Currently I use Xen 4.1.4 and Linux 3.4.xx, with security updates added as and when I get time. Sure there are other places out there to get Xen packages, but more often than not they are untested, out of date or too bleeding edge for production.
Let's get started...
Requirements
* CentOS 5 or CentOS 6 (64Bit Only)
* Appropriate partitioning (Majority of space unallocated and free in a LVM Volume Group)
* Some spare time
CentOS 5
1. Install my GPG key to ensure only signed packages are installed should there ever be an issue with the repo
rpm --import http://repo.smartservermanagement.com/RPM-GPG-KEY-SSM2. Create a new yum .repo file with your favourite editor:
nano /etc/yum.repos.d/ssm.repoNext paste in:
[smartservermanagement]3. Install Xen
name=SmartServerManagement Repository
baseurl=http://repo.smartservermanagement.com/el$releasever/$basearch/
gpgcheck=1
enabled=1
yum install xen kernel-xen4. Next we keed to configure grub. Open /etc/grub.conf with your favourite editor:
nano /etc/yum.repos.d/ssm.repo5. It should look something like the entry below, add the dom0_mem entry to your kernel, depending on how much RAM your server has and how many VPS you intend to host, you should set between 512MB and 4096MB.
title CentOS (2.6.18-348.1.1.el5xen)Note: In some cases you may need to append pci=nomsi to the end of the kernel entry.
root (hd0,0)
kernel /boot/xen.gz-4.1.4 dom0_mem=1024m
module /boot/vmlinuz-2.6.18-348.1.1.el5xen ro root=LABEL=/
module /boot/initrd-2.6.18-348.1.1.el5xen.img
6. Once you are happy, check that Xen is set as the first kernel to boot, and restart your system.
CentOS 6
1. Install my GPG key to ensure only signed packages are installed should there ever be an issue with the reporpm --import http://repo.smartservermanagement.com/RPM-GPG-KEY-SSM2. Create a new yum .repo file with your favourite editor:
nano /etc/yum.repos.d/ssm.repoNext paste in:
[smartservermanagement]3. Install Xen
name=SmartServerManagement Repository
baseurl=http://repo.smartservermanagement.com/el$releasever/$basearch/
gpgcheck=1
enabled=1
yum install xen kernel-xen4. Next we keed to configure grub. Open /etc/grub.conf with your favourite editor:
nano /etc/yum.repos.d/ssm.repo5. It should look something like the entry below.
title CentOS (3.4.29-1.el6xen.x86_64)initrd /boot/initramfs-3.4.29-1.el6xen.x86_64.img
root (hd0,0)
kernel /boot/vmlinuz-3.4.29-1.el6xen.x86_64 ro root=UUID=2d68d0d5-985d-496a-88a4-67bb3c8b4a46 rhgb quiet
6. Notice that although our Dom0 capable kernel has been installed, the Xen kernel itself is not automatically added so you need to add this in, then the linux kernel and initrd (ramdisk) become modules of the xen kernel.
Look at our example below.
Pay attention to the path, if your system has a dedicated /boot partition it may just say /<filename> instead of /boot/<filename>
title CentOS (3.4.29-1.el6xen.x86_64)7. Next you need to add your Dom0 memory limit, as on CentOS 5 this is usually between 512M to 4096M depending on the size of your machine and how many VPS you want to host.
root (hd0,0)
kernel /boot/xen.gz
module /boot/vmlinuz-3.4.29-1.el6xen.x86_64 ro root=UUID=2d68d0d5-985d-496a-88a4-67bb3c8b4a46 rhgb quiet
module /boot/initramfs-3.4.29-1.el6xen.x86_64.img
On CentOS 6 systems we also need to tell the Linux kernel how much memory it has with the mem= option.
Example (Scroll to the right to see the mem= option:
title CentOS (3.4.29-1.el6xen.x86_64)Note: I recommend no less than 1GB Dom0 memory for CentOS 6 systems, on some hardware you lose some usable memory due to an addressing bug/issue in the PV_OPS framework. Adding the mem= option onto the Linux kernel helps alleviate that issue but its not 100%.
root (hd0,0)
kernel /boot/xen.gz dom0_mem=1024M
module /boot/vmlinuz-3.4.29-1.el6xen.x86_64 ro root=UUID=2d68d0d5-985d-496a-88a4-67bb3c8b4a46 rhgb quiet mem=1024M
module /boot/initramfs-3.4.29-1.el6xen.x86_64.img
6. Once you are happy, check that Xen is set as the first kernel to boot, and restart your system.
After your reboot, check to see if Xen is running
Should look something like this...
[root@my ~]# xm info
host : my.server.com
release : 3.4.29-1.el6xen.x86_64
version : #1 SMP Thu Jan 31 18:21:40 GMT 2013
machine : x86_64
nr_cpus : 8
nr_nodes : 1
cores_per_socket : 4
threads_per_core : 2
cpu_mhz : 3400
hw_caps : bfebfbff:28100800:00000000:00007f40:73bae3ff:00000000:00000001:00000281
virt_caps : hvm hvm_directio
total_memory : 32648
free_memory : 12634
free_cpus : 0
xen_major : 4
xen_minor : 1
xen_extra : .4
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler : credit
xen_pagesize : 4096
platform_params : virt_start=0xffff800000000000
xen_changeset : unavailable
xen_commandline : dom0_mem=1024M
cc_compiler : gcc version 4.4.6 20120305 (Red Hat 4.4.6-4) (GCC)
cc_compile_by : mockbuild
cc_compile_domain : smartservermanagement.com
cc_compile_date : Fri Jan 18 13:12:04 GMT 2013
xend_config_format : 4
Questions / Answers / What to do if you get stuck?
* If you are using CentOS 6, you will be running a kernel newer than most distro's, so you may need to use Pygrub if they fail to boot.
* DHCP does not work for Xen HVM, SolusVM currently doesn't write the configuration for compatibility on CentOS 6. Hopefully this will be addressed eventually.
* If you think you've found a bug, please PM Me with the issue + fix and I will add it in.
* The CentOS 6 kernel is based around a modified version of the RedHat .spec so hardware compatibility should be pretty good, if there is a piece of hardware not supported, let me know.
* This is 100% free, but I dont have time to provide free support for everyone so if you get stuck, post a reply, and I'm sure someone will be able to help. Or drop me a PM and for a small fee I can do the install for you + various other bits and pieces.
Thanks, and happy hosting!
Chris
