1. Introducing XenServer 1/2 Monforte Salvatore CCR – Virtualization Tutorial Catania 1-3 December 2010

2. Introducing Citrix XenServer Citrix XenServer is a complete server virtualization platform, optimized for both Windows and Linux virtual servers, with all the capabilities required to create and manage a virtual infrastructure XenServer is a Bare-Metal Type1 Hypervisor ▫ runs directly on server hardware without requiring an additional underlying operating system  this results in a very efficient and scalable system

3. Introducing Citrix XenServer Major features in XenServer ▫ Role Based Access Control  to enable you to control, at both broad and granular levels, which actions different types of administrators can perform in your virtualized environment. ▫ Dynamic Memory Control  allowing you to change the amount of physical memory assigned to a virtual machine without rebooting it ▫ VM snapshot management  including support for snapshots with or without memory, and snapshot rollback for a quick backup and restore mechanism ▫ Access to VM consoles  VNC for installation-time, Xvnc for graphical displays on Linux, and Remote Desktop for Windows ▫ XenSearch  searching, sorting, filtering, and grouping, using folders, tags and custom fields ▫ Complete resource pool management ▫ High availability configuration  both for VMs and core Services ▫ Workload Balancing  pool-wide VMs load balancing ▫ Workload Reports  giving performance views over time and across the datacenter ▫ Performance metrics display

4. Introducing Citrix XenServer XenServer Free data center consolidation back-up restore cloning failure recovery resource balancing automatic VMs placement manual via scripting/programming SDK XenServer Advanced VMs High availabilty Dynamic Memory Control Performance alerting/reporting XenServer Enterprise Role –based administration Live memory snapshots Automated workload balancing

5. Introducing Citrix XenServer

6. Citrix XenServer Overview XenServer hosts and resource pools ▫ add and remove XenServer hosts from pools ▫ create shared storage and attach it to a pool ▫ start VMs on different XenServer hosts within a pool ▫ live migrate running VMs between XenServer hosts within a pool XenServer network configuration ▫ configure physical networking on XenServer hosts and resource pools ▫ create virtual network interfaces for VMs, and bridge these to physical networks ▫ work with VLANs XenServer storage configuration ▫ create shared and local storage repositories on a variety of different substrates (iSCSI, NFS) ▫ create virtual disk images within storage repositories as part of the process of installing VMs ▫ manage and administer storage repositories XenServer VMs management XenServer Backups / Snapshots XenServer SDKs and scripting

7. Introducing Citrix XenServer System Requirements ▫ XenServer requires at least two separate physical x86 computers  XenServer hostand  dedicated entirely to the task of hosting VMs and is not used for other applications  XenCenter application  any general-purpose Windows computer XenServer host system requirements ▫ 64-bit x86 server-class machine  XenServer can make use of up to 256 GB of RAM, up to 16 NICs and up to 64 logical processors The following are the system requirements for the XenServer host:

8. Introducing Citrix XenServer Windows ▫ Windows Server 2008 64-bit & 32-bit ▫ Windows Server 2003 32-bit SP0, SP1, SP2, R2; 64-bit SP2 ▫ Windows Small Business Server 2003 32-bit SP0, SP1, SP2, R2 ▫ Windows XP 32-bit SP 2, SP3 ▫ Windows 2000 32-bit SP 4 ▫ Windows Vista 32-bit SP 1 ▫ Windows 7 32-bit/64-bit Linux ▫ Red Hat Enterprise Linux 32-bit 3.5, 3.6, 3.7, 4.1, 4.2, 4.3, 4.4, 4.5, 4.7, 5.0, 5.1, 5.2; 64-bit 5.0, 5.1, 5.2 ▫ Novell SUSE Linux Enterprise Server 32-bit 9 SP2, SP3, SP4; 10 SP1; 64-bit 10 SP1, SP2 ▫ CentOS 32-bit 4.1, 4.2, 4.3, 4.4, 4.5, 5.0, 5.1, 5.2; 64-bit 5.0, 5.1, 5.2 ▫ Oracle Enterprise Linux 64-bit & 32-bit 5.0, 5.1 ▫ Debian sarge (3.1), etch (4.0)

9. Introducing Citrix XenServer Methods of administering XenServer Different methods of administering XenServer ▫ XenCenter  You can administer XenServer remotely using its graphical, Windows-based user interface  manage servers, resource pools and shared storage, and deploy, manage, and monitor virtual machines from your Windows desktop machine ▫ OpenXenManager  Open source clone of Citrix's XenServer XenCenter  is written in python using the XML-RPC based XenServer API ▫ Command-line Interface (CLI)  You can use the Linux-based xe commands, also known as the CLI, on the host to administer XenServer  xe commands are described in the XenServer Administrator's Guide

10. Installing Citrix XenServer Installing the XenServer host The XenServer host must be installed on a dedicated 64-bit x86 server ▫ simplified text based linux installation ▫ upgrade choice if it is run on a server that already has a previous version of XenServer on it  follows the first-time installation process  existing settings for networking configuration, system time setting and so on are retained ▫ Do not install any other operating system in a dual-boot configuration with the XenServer host The major components of Citrix XenServer are packaged as ISO images, which must be burned onto CDs before use ▫ The product installer includes XenServer, the XenCenter administration console installer, and product documentation  431 MB ▫ Linux Guest Support includes templates and other tools required for support of Linux guests  121 MB

11. Installing Citrix XenServer Once the system has been restarted at the end of the installation process XenServer boots on the XSConsole ▫ text-based administration console which can be used to configure the hypervisor from a console to the server ▫ for remote administration, xsconsole can be accessed through SSH  SSH is enabled for root login by default for XenServer, and once you are in an SSH session, simply type "xsconsole".

12. XenServer hosts and resource pools Resource Pool comprises multiple XenServer host installations, bound together into a single managed entity which can host Virtual Machines ▫ when combined with shared storage VMs can be started on any XenServer host which has sufficient memory and then dynamically moved between XenServer hosts while running  If an individual XenServer host suffers a hardware failure then the administrator can restart the failed VMs on another XenServer host in the same resource pool  If high availability (HA) is enabled on the resource pool, VMs will automatically be moved if their host fails A pool always has at least one physical node, known as the master ▫ other physical nodes join existing pools are described as members Only the master node exposes its administration interface and will forward commands to individual members as necessary ▫ used by XenCenter and the CLI XS Pool Shared Storage Master XS server

13. XenServer hosts and resource pools Requirements for creating resource pools XenServer homogeneous host: ▫ each CPU is from the same vendor  in particular AMD-V and Intel VT CPUs cannot be mixed ▫ each CPU is the same model (except for stepping) ▫ each CPU has the same feature flags ▫ all hosts are running the same version of XenServer software In practice, it is often difficult to obtain multiple servers with the exact same CPUs, and so minor variations are permitted ▫ If you are sure that it is acceptable in your environment for hosts with varying CPUs to be part of the same resource pool, then the pool joining operation can be forced In addition to being homogeneous, an individual XenServer host can only join a resource pool if ▫ it has a static IP address  either manually assigned or via DHCP ▫ it is not a member of an existing resource pool ▫ its clock is synchronized to the same time source as the pool master  for example, via NTP ▫ it has no shared storage configured ▫ there are no running or suspended VMs on the XenServer host which is joining ▫ there are no active operations on the VMs in progress  such as one shutting down ▫ the management NIC of the XenServer host which is joining is not part of a NIC bond XenServer hosts in resource pools may contain ▫ different numbers of physical network interfaces ▫ Local storage repositories of varying size

14. XenServer hosts and resource pools Creating a Resource Pool Resource pools can be created using either the XenCenter management console or the CLI The joining host synchronizes its local database with the pool-wide one, and inherits some settings: ▫ shared storage repositories in the pool  SR configuration created so that the new host can access existing shared storage automatically ▫ networking information is partially inherited  the structural details of NICs, VLANs and bonded interfaces are all inherited  policy information is not i.e. IP addresses of management NICs

15. XenServer hosts and resource pools To join XenServer hosts host1 and host2 into a resource pool via the CLI open a console on XenServer host host2 command XenServer host host2 to join the pool on XenServer host host1 by issuing the command: To remove a host b from a resource pool using the CLI open a console on any host in the pool find the UUID of the host b using the command eject the host from the pool: The XenServer host will be ejected and left in a freshly-installed state xe pool-join master-address= master-username= master-password= [--force ] xe pool-list xe pool-eject host-uuid= Warning Do not eject a host from a resource pool if it contains important data stored on its local disks. All of the data will be erased upon ejection from the pool. If you wish to preserve this data, copy the VM to shared storage on the pool first using XenCenter, or the xe vm-copy CLI command.

16. XenServer networking Networking XenServer networking operates at Layer 2 of the OSI ▫ types of server-side software objects which represent networking entities  PIF, represents a physical network interface on a XenServer host ▫ name and description, a globally unique UUID, the parameters of the NIC that they represent, and the network and server they are connected to  VIF, represents a virtual interface on a Virtual Machine ▫ name and description, a globally unique UUID, and the network and VM they are connected to  Network, which is a virtual ethernet switch on a XenServer host ▫ name and description, a globally unique UUID, and the collection of VIFs and PIFs connected to them Both XenCenter and the CLI allow ▫ configuration of networking options ▫ control over which NIC is used for management operations ▫ creation of advanced networking features  VLANs, NIC bonds, QoS XenCenter hides much of the complexity of XenServer networking

17. XenServer networking MAC Addressing Two important bits really matter when assigning a MAC address ▫ first and second least significant bits of the first leftmost byte in a MAC address  a user-specified Xen Network MAC address should at least be a unicast MAC address, and probably locally administered ▫ basically the 2nd hex digit should be one of: 2, 6, A or E

18. XenServer networking Initial Network Configuration PIFs are created for each NIC in the host ▫ PIF of the NIC selected for use as the management interface is configured with the IP addressing options specified during installation ▫ all other PIFs are left unconfigured a network is created for each PIF ▫ "network 0", "network 1", etc. each network is connected to one PIF Initial networking configuration allows connection to the XenServer host by XenCenter, the xe CLI, and any other management software running separate machines via the IP address of the management interface External networking for VMs is achieved by bridging PIFs to VIFs via the Network Object which acts as a virtual Ethernet switch

19. XenServer networking XenServer host has one or more networks, which are virtual Ethernet switches ▫ Networks without an association to a PIF  considered internal, ▫ used to provide connectivity only between VMs on a given XenServer host, with no connection to the outside world ▫ Networks with a PIF association  considered external ▫ provide a bridge between VIFs and the PIF connected to the network, enabling connectivity to resources available through the PIF's NIC pif0 nic0 xenbr0 XenServer Host DOM 0 VMs DOM U external network vif0 vif2 vif3 internal network vif1

20. XenServer networking In the case of creating a VLAN, ▫ every distinct VLAN will get its own bridge ▫ the bridge name will start with “xapi” ▫ the (pseudo) PIF will have a dot separated name to include the vlan tag number  apart from that, everything else will be the same as normal external network It is not possible to create an internal VLAN network. pif0 nic0 xenbr0 XenServer Host DOM 0 VMs DOM U external network vif0 vif1 vlan5 xapi5 pif0.5 vif4 vif5 vlan10 xapi10 pif0.10 vif2 vif3 to VLAN trunk

21. XenServer introducing Storage XenServer Storage A key object in XenServer storage is a Storage Repository (SR) ▫ physical on-disk structure or format imposed on the available physical storage by XenServer ▫ built-in support for ▫ IDE, SATA, SCSI and SAS drives locally connected ▫ iSCSI, NFS and Fibre Channel (HBA) remotely connected XenServer allocates Virtual Disk Images (VDI) on an SR ▫ this is what a VM sees as a physical disk Each XenServer host can use multiple SRs and different SR types simultaneously SRs can be shared or dedicated between hosts  If the SR is shared, a VDI can be started on any XenServer host in a resource pool that can access that SR

22. XenServer introducing Storage Types of server-side software objects which represent storage entities ▫ Storage Repositories (SRs)  are storage targets containing homogeneous virtual disks (VDIs) ▫ Physical Block Devices (PBDs)  represent the interface between a physical server and an attached SR. PBDs are connector objects that allow a given SR to be mapped to a XenServer host ▫ Virtual Disk Images (VDIs)  are an on-disk representation of a virtual disk provided to a VM. VDIs are the fundamental unit of virtualized storage in XenServer. ▫ Virtual Block Devices (VBDs)  are a connector object that allows mappings between VDIs and VMs SR VDI VBD PBD XenServer VM VBD

23. XenServer introducing Storage Storage Attributes ▫ Shared  storage is based on a Storage Area Network (SAN) or NFS, and so can inherently be shared by multiple XenServers in a pool ▫ Sparse allocation  expansion of a VDI file is allocated as the VM writes data to it  the VM is writing to what it thinks is a local drive ▫ the VM VDI files take up only as much space as is required ▫ Resizable  the size of a detached VDI can be increased ▫ the VM operating system should have the capability to extend into the new space ▫ Fast Cloning  if a VM is cloned, the resulting VMs will share the common on-disk data at the time of cloning  each VM proceed to make its own changes in an isolated copy-on-write (CoW) version of the VDI ▫ VM can be cloned almost instantaneously because the space is allocated on an as-needed basis

24. XenServer introducing Storage VDI types depending on the type of SR a VDI is contained in ▫ VHD  essentially flat files stored either on an NFS SR or a local storage external SR ▫ supports sparse allocation and fast cloning ▫ shareable when the containing SR is of type NFS ▫ supports snapshots without the need for support from the storage back- end ▫ LVM  used on a raw block device (either local or SAN-based), VDI ends up being a Logical Volume (LV) in a Volume Group (VG) ▫ supports VDI resizing ▫ sharable when he storage originates from a SAN depending on the supported Storage Appliance  plugins supported by third parties may be added to /opt/xensource/sm directory ▫ NETApp/DELL EqualLogic  VDIs ends up as a LUN in the SA Volume ▫ supports sparse allocation, VDI resizing, fast cloning, and is shareable

25. XenServer introducing Storage VDI types depending on the type of SR it is contained ▫ VHD  essentially flat files stored either on an NFS SR or a local storage external SR ▫ supports sparse allocation and fast cloning ▫ shareable when the containing SR is of type NFS ▫ supports snapshots without the need for support from the storage back- end ▫ LVM  used on a raw block device (either local or SAN-based), VDI ends up being a Logical Volume (LV) in a Volume Group (VG) ▫ supports VDI resizing ▫ sharable when he storage originates from a SAN depending on the supported Storage Appliance  plugins supported by third parties may be added to /opt/xensource/sm directory ▫ NETApp/DELL EqualLogic  VDIs ends up as a LUN in the SA Volume ▫ supports sparse allocation, VDI resizing, fast cloning, and is shareable

26. XenServer creating VMs VMs running on XenServer may operates in the following mode ▫ Para-Virtualizaition (PV) ▫ Hardware-assisted Virtualization (HVM) Guest OS installation methods ▫ Para-virtualized Kernel support, including vendor installer  PV mode, installs straight into PV mode from vendor media ▫ Para-virtualized Kernel support, without vendor installer  HVM mode  can be switched into PV mode by installing/enabling PV kernel mode ▫ Fully virtualized with Para-virtual Drivers  HVM mode  PV drivers available for post-install ▫ use for Windows guests ▫ Fully virtualized without Para-virtual Drivers  HVM mode  no PV option available and use the "Other install media" option template

27. XenServer creating VMs Creating VMs VMs are created from templates ▫ contain all the various configuration settings to instantiate a specific VM When you want to create a new VM, you must create the VM using a template for the operating system you want to run on the VM The Linux templates create Pure Virtual (PV) guests, as opposed to the HVM guests created by the Windows and Other Install Media templates ▫ block devices are passed through as PV devices  XenServer does not attempt to emulate SCSI or IDE ▫ provides access to PV drviers through xvd* devices Additionally, VMs can be created by: ▫ importing an existing, exported VM ▫ converting an existing VM to a template

28. XenServer creating VMs Installing Linux VMs Installing a Linux VM requires using a process such as the following: ▫ create the VM for your target operating system using the New VM wizard or the CLI ▫ install the operating system using vendor's installation media ▫ install the correct kernel version, if applicable. ▫ install the Linux Guest Agent so that information about the VM appears in XenCenter and the CLI XenServer supports the installation of many Linux distributions as VMs ▫ there are four installation mechanisms:  complete distributions provided as built-in templates  using the vendor media in the server's physical DVD/CD drive  using the vendor media to perform a network installation  installing from an ISO library Installing Linux VMs requires the Linux Pack to be installed onto the XenServer host ▫ Linux Pack can be also installed after XenServer installation  xe-install-supplemental-pack

29. XenServer creating VMs Create a new VM based from the"CentOS 5.5 (32-bit)”

30. XenServer creating VMs Give the new VM a name.

31. XenServer creating VMs Select as the source for the CentOS installation media a network URL (FTP/NFS/HTTP)

32. XenServer creating VMs Select automatic placement of home server for VM if possible.

33. XenServer creating VMs Select required CPU and Memory settings for VM ▫ Note that they can also be changed later on when needed.

34. XenServer creating VMs Add virtual disk storage

35. XenServer creating VMs Select the required virtual network interface

36. XenServer creating VMs Finish VM creation and ensure VM is set to start automatically ▫ If you don't start it automatically you can if so required alter certain settings like for instance providing a kickstart file  under Advanced OS Boot parameters

37. XenServer creating VMs Continue the wizard as any normal CentOS installation

38. XenServer creating VMs Once the VM has rebooted ▫ Install the Linux Guest Agent by selecting the xs-tools.iso into the Virtual DVD Drive of your VM  then issue the following  or directly install xe-guest-utilities-5.6.0-???.{i386,x86_84,amd64}.{rpm, deb} xe-guest-utilities-xenstore-5.6.0-???.{i386,x86_84,amd64}.{rpm, deb}  most suitable to the just installed Linux Distribution #mount /dev/xvdd /media #cd /media/Linux #./install.sh

39. XenServer: How To Extend VM disk size How To Extend the Virtual Disk Size of a Xen Virtual Machine Shut down the corresponding virtual machine ▫ XenCenter  click on Storage tab of the VM  select the VDI to extend and open Properties dialog  select Size and Location  change the size of the VDI ▫ CLI  find the VDI Universally Unique Identifier (UUID) by running the following command:  run the following command to resize the virtual disk: After resizing the disk in XenServer start the operating system ▫ add single to VM boot options if you want to resize the system volume  execute the following commands: xe vm-disk-list vm= xe vdi-resize size=uuid= size= #e2fsck -f /dev/xvd #resize2fs /dev/xvd #fdisk /dev/xvd #d (Delete the partition and recreate it) #n (New partition) #w (Write out table) #pvresize/dev/xvd #lvextend –l100%PV /dev/mapper/ - for ext3 FS execute then following and reboot: for lvm FS execute then following and reboot:

40. XenServer: How To Switch from HVM to PV mode How To Switch from HVM to PV mode As a condition for ParaVirtualization to work, a kernel that supports the Xen hypervisor needs to be installed and booted in the virtual machine ▫ boot the virtual machine and open the console and install the Linux Xen kernel ▫ build a new initrd without the SCSI drivers and with the xen PV drivers ▫ modify the grub boot loader menu  /boot/grub/menu.lst ▫ remove the kernel entry with ‘gz’ in the name ▫ rename the first “module” entry to “kernel” ▫ rename the second “module” entry to “initrd” ▫ correct the *.img pointer to the new initrd*.img ▫ edit the line “default=” to point to the modified xen kernel entry ▫ save the changes ▫ shutdown but do not reboot the machine yum install kernel-xen cd /boot mkinitrd --omit-scsi-modules --with=xennet --with=xenblk --preload=xenblk \ initrd-$(uname -r)xen-no-scsi.img $(uname -r)xen

41. XenServer: How To Switch from HVM to PV mode How To Switch from HVM to PV mode As a condition for ParaVirtualization to work, a kernel that supports the Xen hypervisor needs to be installed and booted in the virtual machine ▫ boot the virtual machine and open the console and install the Linux Xen kernel ▫ build a new initrd without the SCSI drivers and with the xen PV drivers ▫ modify the grub boot loader menu  /boot/grub/menu.lst ▫ remove the kernel entry with ‘gz’ in the name ▫ rename the first “module” entry to “kernel” ▫ rename the second “module” entry to “initrd” ▫ correct the *.img pointer to the new initrd*.img ▫ edit the line “default=” to point to the modified xen kernel entry yum install kernel-xen cd /boot mkinitrd --omit-scsi-modules --with=xennet --with=xenblk --preload=xenblk \ initrd-$(uname -r)xen-no-scsi.img $(uname -r)xen

42. XenServer: How To Switch from HVM to PV mode Edit the VM record of to convert it to PV boot mode ▫ clear the HVM boot mode ▫ set pygrub as boot loader ▫ find the UUID of VDI and set the bootable flag to the related VBD xe vm-param-set uuid= HVM-boot-policy=”” xe vm-param-set uuid= PV-bootloader=pygrub xe vm-disk-list uuid= xe vbd-param-set uuid= bootable=true