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Xen Virtualization Andrew Hamilton TJHSST CSL Logo and Powered By Linux by Dan Tran tjhsst.edu/~dtran.

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Presentation on theme: "Xen Virtualization Andrew Hamilton TJHSST CSL Logo and Powered By Linux by Dan Tran tjhsst.edu/~dtran."— Presentation transcript:

1 Xen Virtualization Andrew Hamilton TJHSST CSL Logo and Powered By Linux by Dan Tran tjhsst.edu/~dtran

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 – 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 – 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 eth0 xenbr0 Vif0.0Vif1.0Vif2.0 Network Bridge Physical Adapter Network VMs

11 VM Networking: NAT Switch eth0 IPTables Vif0.0Vif1.0Vif2.0 NAT/Firewall Physical Adapter Network 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? – 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 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) – 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) – 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 This Presentation – Sysadmin Livedoc, lots of general knowledge about Linux/UNIX – Homepage of the Xen project. A Few Resources

20 Any Questions?


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