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Xen Virtualization Andrew Hamilton

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1 Xen Virtualization Andrew Hamilton
TJHSST CSL Logo and Powered By Linux by Dan Tran

2 Presentation Overview
Theory Methods of Virtualizing Xen Virtualization Conclusion

3 Theory Do one thing and do it well (The UNIX philosophy)
Containerize Systems Many little machines contained in one

4 Methods of Virtualization
Chroots Minimal Overhead One kernel, network connection, process system Root can break out FreeBSD Jails / Solaris Containers Separate Networking and process systems, root is trapped Overhead is still minimal Still only one kernel

5 More Methods of Virtualization
Full Virtualization Multiple OSes, complete segregation of resources High overhead, oftentimes expensive Paravirtualization (Xen/LDOMs) Multiple Oses with less overhead May require specialized hardware or a modified operating system

6 Xen Virtualization

7 What we have Hypervisor Dom0 DomUs
Runs underneath everything and serves as an interface between the hardware and the VMs The Xen part of Xen Virtualization Dom0 Generally a linux kernel with the xen patches Is able to control the hypervisor and manage VMs Needs drivers for the server hardware DomUs The VMs we want to run

8 Installing a Dom0 First install and configure the linux distribution of your choice Then install the xen-specific packages Debian: apt-get install xen-linux-image Gentoo: emerge xen, xen-tools, xen-sources Red Hat: yum install xen kernel-xen

9 Configuring the Dom0 Grub VM Storage Space Setup VM Networking
Boot using the Xen hypervisor as the kernel Load the Dom0 Kernel as a Module Start xend on boot VM Storage Space Local vs SAN Files or LVM (or other devices) Setup VM Networking Bridging or NAT

10 VM Networking: Bridging
Switch Network eth0 Physical Adapter xenbr0 Network Bridge Vif0.0 Vif1.0 Vif2.0 VMs

11 VM Networking: NAT Switch eth0 IPTables Vif0.0 Vif1.0 Vif2.0 Network
Physical Adapter IPTables NAT/Firewall Vif0.0 Vif1.0 Vif2.0 VMs

12 Testing Time! Reboot to the Xen Setup (hopefully it boots)
Stress Test the new setup Recompiling the kernel repeated works well For a in `seq 1 20`; do make clean; make; done; Make sure everything works well now If it doesn’t fix it now

13 Creating VMs Manual or automatic? File-based vs Device-based
Xen-tools File-based vs Device-based Create the harddrives LVM create the logical volumes Files, create the files Format the disks

14 Linux VMs Mount the hard-drives
Use an appropriate method to install your OS Debootstrap Untar and chroot Copy over an image Remember VMs only need a small set of packages

15 Xen Config Files kernel = ‘/boot/kernel-2.6.29-r1-amd64-xen-domu
Initrd (if required) Memory = ‘512’ Disk = [ ‘phy:vgmagellanic/ns1- disk,sda1,w’ file:/home/xen/ns1- swap,sda2,w’ ] Name = ‘ns1’ vif = [ 'mac=00:02:C6:26:10:B7‘, ‘mac=00:16:3e:aa:bb:cc,bridge=xenbr1’ ]

16 Managing VMs Starting VMs (xm create) Stopping VMs (xm shutdown)
We usually want to be running VMs Stopping VMs (xm shutdown) This is the nice safe way to stop VMs Really Stopping VMs (xm destroy) The Xen equivalent of a four-second off Monitoring (xm list, xm top)

17 Advanced Features Live Migration (xm migrate) Snapshotting for backups
Enable in xend config Both servers need to be able to access the VM’s disks Snapshotting for backups Using lvm to make consistent backups Snapshot the domu from the dom0 Mount the snapshot and rsync or tar it

18 Conclusion Xen can provide a separation of services with minimal performance hit It is NOT a guaranteed security measure, but it’s pretty good Some programs dislike running in VMs Allows Virtualization on older x86 hardware

19 A Few Resources
This Presentation Sysadmin Livedoc, lots of general knowledge about Linux/UNIX Homepage of the Xen project.

20 Any Questions?

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