Virtualization on Linux Using KVM and libvirt. Matt Surico Long Island Linux Users Group 11 March, 2014

Transcription

1 Virtualization on Linux Using KVM and libvirt Matt Surico Long Island Linux Users Group 11 March, 2014

2 What will we talk about? Rationalizing virtualization Virtualization basics How does it work under Linux? Setting up a virtual host Live demo of libvirt and KVM in action!

3 Why virtualize? - Part 1 Physical space savings and, if required, transportability

4 Why virtualize? - Part 2 Reduced consumption of energy (and lower power bills)

5 Other reasons to virtualize Ease of creating new servers (cloning) Ad-hoc projects (proof of concept) Experimentation with new distributions Self-Instructional situations Anyone else with a virtualization use case?

6 Virtualization Architecture One key component is the hypervisor. A hypervisor is software (or hardware, or even firmware) that creates an interface between a guest operating system and a virtual host so that virtual machines can be run. The hypervisor's job is to create and/or to present a virtual operating platform to the virtual machine (an abstraction).

7 Hypervisor Diagrams We will briefly look at two general types of hypervisors: Native (aka Bare Metal, or Type 1 ) Hosted (aka Type 2 )

8 Bare Metal Hypervisor Examples: Citrix Xen, VMWare ESX/ESXi

9 Hosted Hypervisor Examples: VirtualBox and KVM

10 KVM Simply put, this allows the Linux kernel to be a hypervisor Has been in the kernel mainline since Contains virtualization extensions (Intel VT and AMD-V), and loadable kernel modules (kvm.ko plus either kvm-intel.ko or kvm-amd.ko) Exposes the /dev/kvm interface to a host running in user space (typically QEMU)

11 libvirt C library with package bindings for many other languages like Ruby, Java, python, perl, etc. A toolkit for managing virtualization Provides: Remote management using TLS encryption and x509 certificates Remote management authenticating with Kerberos and SASL Local access control using PolicyKit Zero-conf discovery using Avahi multicast-dns Management of virtual machines, virtual networks and storage Portable client API for Linux, Solaris and Windows

12 libvirt diagram

13 How to check your CPU Use /proc/cpuinfo and look at the flags. There are different flags for Intel vs. AMD Intel vmx = Intel VT-x (basic virtualization) - required ept = Extended Page Tables vpid = decreases TLB flushes during context switching between guests AMD svm = AMD SVM (basic virtualization) - required npt = AMD nested page tables (like Intel's EPT)

14 Building the demo We'll take a brief walk through the steps taken to prepare the laptop for today's demo Verify the CPU will work Add storage to laptop Install CentOS 6.4 (the host OS) Include virtualization packages Once these steps are done, virtual machines can be provisioned

15 Build: CPU/RAM The CPU in the laptop is AMD A4-3305M (dual core, 800 MHz, 512 KB cache) The command used to check the processor was: ~]$ grep flags /proc/cpuinfo uniq flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nonstop_tsc extd_apicid aperfmperf pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt cpb npt lbrv svm_lock nrip_save pausefilter Laptop has 3 GB RAM FYI: Home machine (dedicated virtual host) has Intel(R) Core(TM) i5-3570k CPU, quad core, 3.40GHz, 6144 KB cache with 8 GB RAM

16 Build: Adding storage Laptop has a single internal hard drive, dual boot Ubuntu and a certain proprietary OS that came with the laptop. Current hard drive didn't have enough space to setup a third operating system plus the virtual disks for multiple VMs Used an external USB 3.0 drive (500 GB) Allows for total removal of the storage to operate the laptop normally.

17 Build: Partitioning storage During the installation of CentOS 6.4, the external drive showed up as /dev/sdb, so it was partitioned as such: /dev/sdb1 = /boot (1 GB) /dev/sdb2 = swap (4 GB) /dev/sdb3 = Physical Volume for LVM (the rest of the drive) vg_kvm = Volume Group (~460 GB) 334 GB allocated to logical volumes

18 Build: Logical Volumes ~]$ sudo lvs vg_kvm LV VG Attr LSize libvirtkvmlv vg_kvm -wi-ao g rootkvmlv vg_kvm -wi-ao g usrkvmlv vg_kvm -wi-ao g varkvmlv vg_kvm -wi-ao g /dev/mapper/vg_kvm-libvirtkvmlv on /var/lib/libvirt type ext4 /dev/mapper/vg_kvm-rootkvmlv on / type ext4 /dev/mapper/vg_kvm-usrkvmlv on /usr type ext4 /dev/mapper/vg_kvm-varkvmlv on /var type ext4

19 Build: CentOS installation CentOS 6.4 installed with Virtual Host profile. Also added some other graphical convenience packages Important: under Virtualization, pick Virtualization Tools Ready to start having fun

20 Working with VMs Several Open Source tools available: virsh: command line, provided by libvirt Virtual Machine Manager: GUI ovirt: web application Virt-factory: system management framework

21 Networking One or more virtual networks may be created within the virtual host Virtual machines may be outfitted with one or more virtual NICs The dnsmasq lightweight server provides DNS and DHCP services for the virtual network

22 Networking: libvirt

23 Time for a demo! What we'll see: Use of virsh and virt-manager Creating and managing VMs (including cloning) Creating and managing virtual networks Provisioning additional storage for VMs