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Technical Note

Installing and Configuring

Linux Guest Operating Systems

VMware® Infrastructure 3

DatacenterstodayhaveamixofWindowsandLinuxworkloads.IDCestimatesin2008that68percentofall

physicalserversshippedareWindows‐based,comparedto23percentthatareLinux‐based.However,the

proliferationofLinuxenvironmentsissteadilyincreasing.From2006to2011,IDCforecaststhecompounded

annual

growthrate(CAGR)ofphysicalserverunitsrunningLinuxat28.1percent,withWindowstrailingat

25.0percent.AsmoredatacentersarevirtualizedwithVMwareInfrastructure3,itmakessensethatthese

virtualizedenvironmentsarealsotrendingtowardsincreaseduseofLinux.TheCAGRofvirtualserverunits

runningLinux

isforecastedbyIDCat44.1percent,withWindowsbehindat39.0percent.Linuxoperating

systemsnowhostapplicationsfromdatabasestoWebserverstoapplicationservers,muchastheirWindows

counterpartsdo.Linuxguestoperatingsystemsarehere,andVMwareisdedicatedtosupportingthem.

Thistechnicalnotedescribesinstalling,

configuring,updating,andadministeringLinuxguestoperating

systemsinvirtualmachinesrunningonVMwareInfrastructure3version3.5(specificallyVMware

VirtualCenter2.5Update2andVMwareESX3.5Update2).Inaddition,thisnoteincludesacollectionofuseful

tipsandtricksinfine‐tuningyourLinuxvirtualmachines,whichmay

ormaynotapplytoallyourLinuxusage

scenarios.AlthoughtherecommendationsinthispaperapplytomostLinuxdistributions,theyaretailored

specificallytoRedHatEnterpriseLinux5.IDCobservedin2007thatofallpaidLinuxsubscriptions,RedHat

EnterpriseLinuxcameinat62.1percent

andNovellSUSELinuxEnterpriseServerplacedsecondat29percent.

LinuxadministratorscanusethispaperasasourceforguidelineswhenbuildingandmaintainingLinux

virtualmachinesintheirVMwareInfrastructureenvironments.SomeworkingknowledgeofVirtualCenter2.5

Update2,ESX3.5Update2,andLinuxoperatingsystemsis

required.

Thistechnicalnotecoversthefollowingtopics:

 “LinuxSupportonVMwareESX”onpage 2

 “InstallingLinuxinaVirtualMachine”onpage 2

 “InstallingandUpgradingVMwareTools”onpage 4

 “CloningaLinuxGuestOperatingSystem”onpage 9

 “VMwareUpdateManager”onpage 11

 “LinuxTimeSynchronizationRecommendations”onpage 12

 “A d d i t i o n a l Notes”onpage 15

 “Resources”onpage 19

 “AppendixA:LinuxVersionsSupportedonESXServer”onpage 20

 “AppendixB:Command‐LineOptionsforVMw areToolsUpgrades”onpage 21

 “AppendixC:EnablingVMIinaLinuxKernelandinESX3.5”onpage 22

Summary of content (23 pages)

PAGE 1
Technical Note Installing and Configuring Linux Guest Operating Systems VMware® Infrastructure 3 Datacenters today have a mix of Windows and Linux workloads. IDC estimates in 2008 that 68 percent of all physical servers shipped are Windows‐based, compared to 23 percent that are Linux‐based. However, the proliferation of Linux environments is steadily increasing. From 2006 to 2011, IDC forecasts the compounded annual growth rate (CAGR) of physical server units running Linux at 28.
PAGE 2
Installing and Configuring Linux Guest Operating Systems Linux Support on VMware ESX VMware ESX supports the widest range of Linux guest operating systems of any virtualization product. ESX supports Red Hat Enterprise Linux 2.1, 3, 4, and 5, SUSE Linux Enterprise Server 8, 9, and 10, and Ubuntu Linux 7.04, 8.04, and 8.10. In addition, ESX supports almost all updates to these releases as well as specialized variants of them.
PAGE 3
Installing and Configuring Linux Guest Operating Systems Rather than installing from a physical CD‐ROM, you can create an ISO image file from the installation CD‐ROM. Using an ISO image file in this way can be particularly convenient if you need to install the same operating system in multiple virtual machines. You can store the ISO file on the host machine or on a network drive accessible from the host machine.
PAGE 4
Installing and Configuring Linux Guest Operating Systems On Intel platforms, 64‐bit guests can be run only with hardware assist (Intel VT). On AMD platforms 64‐bit guests can be run either with hardware assist (AMD‐V) or using binary translation. A VT virtual machine monitor incurs less overhead on the newer Intel Core 2 processors than on the older Pentium 4 processors. If you have a choice between a 32‐bit or 64‐bit guest, select the 32‐bit guest on older Intel platforms (Pentium 4).
PAGE 5
Installing and Configuring Linux Guest Operating Systems The VMware Tools control panel, which lets you modify settings, shrink virtual disks, and connect and disconnect virtual devices. A set of scripts that helps you automate guest operating system operations. The scripts run when the virtual machine’s power state changes if you configure them to do so.
PAGE 6
Installing and Configuring Linux Guest Operating Systems 7 In an X terminal, as root (su -), run the following file to configure VMware Tools: vmware-config-tools.pl 8 When done, exit from the root account: exit 9 In an X terminal, open the VMware Tools Properties dialog box: vmware-toolbox & To install or upgrade VMware Tools on a Linux guest with the tar installer or RPM installer For enhanced performance, you should install VMware Tools even if you are not running the X Window System.
PAGE 7
Installing and Configuring Linux Guest Operating Systems ./vmware-install.pl Respond to the configuration questions on the screen. Press Enter to accept the default value. The vmware-config-tools.pl script should run automatically at the end of this installation. For the RPM installer, you need to configure VMware Tools by running vmware-config-tools.pl manually: vmware-config-tools.pl VMware Tools is now installed and can be verified in VI Client in the Summary tab of the Linux virtual machine.
PAGE 8
Installing and Configuring Linux Guest Operating Systems Major Components Installed by VMware Tools The major components of VMware Tools when installed include vmblock, vmdesched (to be deprecated in upcoming releases of VMware Tools), vmhgfs, vmmemctl, vmsync, and vmxnet. This section takes a closer look at vmxnet, the component of most interest to Linux administrators. vmxnet vmxnet is a Linux kernel device driver for the VMware high‐speed virtual networking device.
PAGE 9
Installing and Configuring Linux Guest Operating Systems Virtual machines must be hosted on ESX Server 3.0.1 or greater, and the VirtualCenter server must be version 2.0.1 or greater. Virtual machines must be running a guest operating system that is supported by ESX Server 3.0.1 or greater and VirtualCenter 2.0.1 or greater. Virtual machines must be powered on. To manually upgrade VMware Tools: 1 Launch the VI Client and log in to the VirtualCenter server.
PAGE 10
Installing and Configuring Linux Guest Operating Systems The clone or template has a root volume formatted with an ext2, ext3, or ReiserFS file system. NOTE SUSE Linux Enterprise Server distributions register the Ethernet MAC address information in the guest operating system’s configuration files. This causes the process of obtaining IP addresses after cloning to fail.
PAGE 11
Installing and Configuring Linux Guest Operating Systems 6 On the DNS and Domain settings page, enter the IP addresses for the DNS servers. Specify the DNS connections by entering DNS suffixes. For each DNS suffix you enter, click Add. If you are adding multiple DNS connections, use Move Up and Move Down to specify the order in which a virtual machine is to use the connections.
PAGE 12
Installing and Configuring Linux Guest Operating Systems \docroot\vci\guestAgent\. For example, if Update Manager was installed in C:\Program Files\VMware\Infrastructure\Update Manager, the Guest Agent installers are at C:\Program Files\VMware\Infrastructure\Update Manager\docroot\vci\guestAgent\. The Guest Agent requires no user input so that the installation completes silently. In Linux, install the VMware-VCIGuestAgent-Linux.rpm file by issuing the following command: rpm -ivh VMware-VCIGuestAgent-Linux.
PAGE 13
Installing and Configuring Linux Guest Operating Systems For GRUB, put the kernel command line parameters at the end of the kernel line. For example if the kernel line looks like: kernel /vmlinuz-2.6.18 ro root=/dev/hda2 and you want to add clock=pmtmr divider=10, the updated text is: kernel /vmlinuz-2.6.18 ro root=/dev/hda2 clock=pmtmr divider=10 For additional information about working with boot loaders, see your Linux distribution’s documentation. Table 4.
PAGE 14
Installing and Configuring Linux Guest Operating Systems Table 5. Settings for 64-bit Kernels Linux Version Kernel Parameters Notes Red Hat Enterprise Linux 3 (all updates) Has no workaround for lost tick overcompensation. Avoid using if possible. SUSE Linux Enterprise Server 10 SP2 on ESX 3.5 and later Recommended. SUSE Linux Enterprise Server 10 SP2 on ESX Server 3.0.
PAGE 15
Installing and Configuring Linux Guest Operating Systems The configuration directive tinker panic 0 instructs NTP not to give up if it sees a large jump in time. This is important for coping with large time drifts and also resuming virtual machines from their suspended state. NOTE The directive tinker panic 0 must be at the top of the ntp.conf file. It is also important not to use the local clock, often referred to as the undisciplined local clock, as a time source.
PAGE 16
Installing and Configuring Linux Guest Operating Systems Asynchronous I/O Support for asynchronous I/O in the kernel and corresponding system calls are included in Linux kernel version 2.6. But the API for the appropriate system calls differs from the original functions, so a simple recompilation of existing applications might be insufficient to use the new change. The change requires source code modification that has occurred in different applications at different rates.
PAGE 17
Installing and Configuring Linux Guest Operating Systems The mainline Linux kernel has moved to a tickless timekeeping model in which, instead of counting periodic interrupts to tell the time, the Linux kernel queries a hardware time source when it needs to know the time. These changes make Linux a much better‐behaved operating system in physical as well as virtual environments.
PAGE 18
Installing and Configuring Linux Guest Operating Systems The idea of guest‐host interaction is not a new concept. It has long been a part of VMware products in the form of VMware Tools. For example: The VMware SVGA driver shares data structures with the hypervisor to allow faster screen updates. The VMware high‐performance virtual Ethernet driver, vmxnet, shares data structures with the hypervisor to reduce CPU overhead.
PAGE 19
Installing and Configuring Linux Guest Operating Systems When a workload runs in user mode, the VMware virtual machine in which it is running is in direct‐execution mode. Because directly executed code already runs at native speeds in both binary translation and VMI‐style paravirtualization, workloads that spend the majority of their time in user mode gain only modest performance improvements from paravirtualization.
PAGE 20
Installing and Configuring Linux Guest Operating Systems “Improving Guest Operating System Accounting for Descheduled Virtual Machines in ESX Server 3.x Systems” http://www.vmware.com/resources/techresources/526 Instructions on downloading and installing a driver for the BusLogic virtual SCSI adapter http://www.vmware.com/download/esx/drivers_tools.html “Linux Guest Moved to a System with Different Processor Type Panics During Boot” http://kb.vmware.
PAGE 21
Installing and Configuring Linux Guest Operating Systems Table 8. Supported Linux and FreeBSD Operating Systems Guest Operating System ESX Server SUSE Linux Enterprise Server 8 2.0–3.5 U2 SUSE Linux 9.3 2.5.2–2.5.5 SUSE Linux 9.2 2.5.1–2.5.5 SUSE Linux 9.1 2.5–2.5.5 SUSE Linux 9.0 2.1–2.5.5 SUSE Linux 8.2 2.0–2.5.5 Ubuntu Linux 8.04 3.5 U2 Ubuntu Linux 7.10 3.5 U1–U2 Ubuntu Linux 7.04 3.0.2–3.5 U2 FreeBSD 4.11 2.5.4–2.5.5 FreeBSD 4.10 2.5–2.5.5 FreeBSD 4.9 2.
PAGE 22
Installing and Configuring Linux Guest Operating Systems Appendix C: Enabling VMI in a Linux Kernel and in ESX 3.5 To use VMI, you must enable it in your Linux kernel and for the ESX 3.5 virtual machines in which that kernel is running. The following instructions can also be found in the VMware knowledge base article “How to enable a virtual machine interface in a Linux kernel and in ESX Server 3.5.” For a link, see “Resources” on page 19. Enabling VMI in ESX 3.5 In ESX 3.
PAGE 23
Installing and Configuring Linux Guest Operating Systems The presence of the VMI device in the lspci output, however, does not confirm that the guest operating system is running in VMI mode. The following dmesg output confirms VMI mode, indicating that VMI is enabled in the virtual machine settings as well as in the Linux kernel. Detected VMI ROM version 3.0 VMI Timer active. NOTE VMI‐enabled kernels are included in some Linux distributions.