Virtualization with KVM (Kernel-based Virtual Machine)

Virtualization with (KVM)Kernel-based Virtual Machine

Thomas Korber Consultant and TrainerB1 Systems GmbHkorber@b1-systems.de

Bruce RogersConsulting Software EngineerNovell, Inc.brogers@novell.com

First release in early 2007

Originally developed by Qumranet

Included in Linux kernel release 2.6.20

GPL v2

KVM – Full Virtualization

• Relies on AMD's AMD-V or Intel's VT-x virtualization technologies

• Implemented as kernel modules– kvm.ko: provides virtualization infrastructure– kvm_amd.ko and kvm_intel.ko: hardware platform specific

modules for the hardware virtualization technologies

• => Vanilla Linux kernel becomes virtual machine monitor, which can use any kernel infrastructure without modifications

• => KVM virtual machines become regular user-space processes

KVM ArchitectureAdds “Guest Mode” to Traditional Kernel and User Modes

UserspaceProcess

Hardware Support,vitualization technologies for x86

(AMD-V/ Intel-VT)

Linux Kernel

UserspaceProcess ...

Guest UserspaceProcesses

KVM (Module)

QEMU-KVM

Guest Kernel(e.g. Linux Kernel)

Source: “Virtualization with KVM” training, B1 Systems GmbH

Supported Hardware

Any i386/x86_64 CPUs that have AMD-V or VT-x:

=> Almost any server CPU sold in the last couple years

Supported Hardware (Continued)

Utilizes the following additional hardware virtualization features:

VPID / ASID

VT-d/IOMMU

HAP (EPT/NTP)

VMX Unrestricted Guest

SR-IOV

• Community project founded in 2003

• Emulates PC hardware and CPUs

• Since v 0.10.0 support for KVM VMM

• Modified qemu-kvm is user space tool for KVM

• Communication with KVM via /dev/kvm

KVM Features

Supports 32 and 64 bit guests (on 64 bit hosts)

Supports hardware virtualization features

Paravirtualized drivers (virtio): blk, net, clock, balloon

Snapshots

Delta images of virtual machines

PCI passthrough

Kernel samepage merging

KVM Features (continued)

Sound support

CPU, memory and disk over-commit

Live migration

CPU and device hotplug

Non-kvm (emulation only) mode

PXE boot

KVM - Supported Guest Systems

Solaris, OpenSolaris Linux

Windows BSD Unix

KVM Guests Supported by Novell® (I)

Linux - both 32 and 64 bit

• SUSE Linux Enterprise Server 11 SP1 (level 3 supported)

• SUSE Linux Enterprise Desktop 11 SP1 (technical preview)

• Red Hat Enterprise Linux 4 (best effort)• Red Hat Enterprise Linux 5 (best effort)

KVM Guests Supported by Novell® (II)

Microsoft Windows – both 32 and 64 bit

(“best effort” support only)

• Microsoft Windows 2003 SP2+ plus PV drivers

• Microsoft Windows 2008+ plus PV drivers

• Microsoft Windows XP SP3+ plus PV drivers

• Microsoft Windows Vista SP1+ plus PV drivers

Supported Limits

Host RAM and CPU limits are the same with or without kvm modules loaded

Guest RAM size: 512 GB

Virtual CPUs per guest: 16

NICs per guest: 8

Block devices per guest: 4 emulated, 20 para-virtual (virtio-blk)

Maximum number of guests: total vCPUs <= 8 times total CPU cores in Host

Xen and KVM: A Comparison

• Kernel module

• Uses kernel as VMM

• In upstream kernel

• Only supports fully virtualized VMs

• VMM implementation of its own; hypervisor

• Kernel as I/O dispatcher and management domain

• Maintained and supported as a patch to mainline kernel by Novell®

• Supports fully virtualized and paravirtualized Vms

Virtualization in SUSE® Linux Enterprise Server 11 SP1• SUSE Linux Enterprise Server 11 SP1 will ship with

both virtualization solutions (KVM and Xen)

• Xen is the primary solution, being the proven enterprise-ready open source hypervisor

• Long term, Novell® expects KVM eventually to become equivalent to Xen

• Toolset shipped in SUSE Linux Enterprise Server 11 SP1 supports both Xen and KVM

Setting up KVM on SUSE® Linux Enterprise 11 SP1

Demo Setup

• Storage server and installation source:

– SUSE® Linux Enterprise Server 11 GA x86_64

– Logical volume as iSCSI target for OCFS2 file system

– Installation sources (SUSE Linux Enterprise Server 11 SP1 Beta5 and SUSE Linux Enterprise High Availability Extension Server 11 SP1 Beta5) exported via HTTP

• 2 KVM hosts– SUSE Linux Enterprise Server 11 SP1 Beta5 x86_64

– Logical volume for DRBD; DRBD primary/primary setup

Demo Setup – Shared Storage

Node 1 Node 2 Node 3

FC or iSCSI

Demo Setup – Replicated Storage

Node 1 Node 2

TCP/IPDRBD

Local Disk Local Disk

Packages

• KVM, libvirt and virt-manager as GUI

zypper in kvm virt-manager

• (optional) packages for shared storage:

– server: iscsitarget– KVM hosts: open-iscsi, ocfs2-tools, ocfs2-tools-o2cbor

– KVM hosts: drbd, drbd-kmp-default

iSCSI Setup

• Storage Server:storage:~ # cat /etc/ietd.conf | grep -v "#"Target iqn.2009-11.b1-systems.de:lv_shareLun 0 Path=/dev/vg_system/lv_share,Type=fileio

• KVM Hosts:node1:~ # iscsiadm -m discovery -tst -p storage192.168.2.35:3260,1 iqn.2009-11.b1-systems.de:lv_sharenode1:~ # iscsiadm -m node -T iqn.2009-11.b1-systems.de:lv_share -p 192.168.2.35 -l

DRBD Setup - /etc/drbd.conf (I)

Create /etc/drbd.conf and have the identical file on both nodesnode1:~ # cat /etc/drbd.confglobal { usage-count no;}resource r0 { protocol C; syncer { rate 40M; } net { allow-two-primaries; } startup { become-primary-on both; }

DRBD Setup - /etc/drbd.conf (II)

on node1 { device /dev/drbd0; disk /dev/mapper/storage-lv_drbd; address 192.168.2.31:7791; meta-disk internal; } on node2 { device /dev/drbd0; disk /dev/mapper/storage-lv_drbd; address 192.168.2.32:7791; meta-disk internal; }}

DRBD Setup

On both nodes:node1:~ # modprobe drbd && rcdrbd startnode1:~ # drbdadm create r0

On first node:node1:~ # drbdadm -- --overwrite-data-of-peer primary r0

On second node:node1:~ # drbdadm primary r0

On either node:node1:~ # cat /proc/drbd

OCFS2 Setup (I)

node1:~ # vi /etc/ocfs2/cluster.conf

node: name = node1

cluster = ocfs2

number = 0

ip_address = 192.168.2.31

ip_port = 7777

node: name = node2

cluster = ocfs2

number = 1

ip_address = 192.168.2.32

ip_port = 7777

cluster: name = ocfs2

node_count = 2

OCFS2 Setup (II)

node1:~ # rco2cb configureConfiguring the O2CB driver.

This will configure the on-boot properties of the O2CB driver.Load O2CB driver on boot (y/n) [y]: Cluster stack backing O2CB [o2cb]: Cluster to start on boot (Enter "none" to clear) [ocfs2]: Specify heartbeat dead threshold (>=7) [31]: Specify network idle timeout in ms (>=5000) [30000]: Specify network keepalive delay in ms (>=1000) [2000]: Specify network reconnect delay in ms (>=2000) [2000]: Writing O2CB configuration: OKLoading filesystem "configfs": OKMounting configfs filesystem at /sys/kernel/config: OKLoading stack plugin "o2cb": OKLoading filesystem "ocfs2_dlmfs": OKMounting ocfs2_dlmfs filesystem at /dlm: OKSetting cluster stack "o2cb": OKStarting O2CB cluster ocfs2: OK

OCFS2 Setup (III) - iSCSI

node1:~ # mkfs.ocfs2 /dev/disk/by-path/ip-192.168.2.35\:3260-iscsi-iqn.2009-11.b1-systems.de\:lv_share-lun-0

On both nodes:

node1:~ # mount /dev/disk/by-path/ip-192.168.2.35\:3260-iscsi-iqn.2009-11.b1-systems.de\:lv_share-lun-0 /var/lib/kvm/images/

OCFS2 Setup (IV) - DRBD

node1:~ # mkfs.ocfs2 /dev/drbd0

On both nodes:

node1:~ # mount /dev/drbd0 \ /var/lib/kvm/images

KVM VM Installation – GUI

KVM VM Installation: CLI

• qemu-img create \ /var/lib/kvm/images/sles11_raw_disk1.img 5G

• qemu-kvm -hda \/var/lib/kvm/images/sles11_raw_disk1.img \ -cdrom /srv/isos/SLES-11-DVD-x86_64-GM-DVD1.iso \ -boot d -m 512[installation of a “physical computer”]

• qemu-kvm -hda \/var/lib/kvm/images/sles11_raw_disk1.img -m 512

KVM – Installation With vm-installUnattended installation:

vm-install --background --vm-settings=/foo/bar/vm-template.xml --os-settings=/foo/bar/autoinst.xml …

KVM – Networking

• Usermode network stack

– Default setup

– No root permissions needed

– Integrated DHCP, DNS, SMB and DNS

• TAP device

• Bridged mode (comparable to default Xen network setup)

KVM – Networking (II)

Example: bridged setupnode1:~ # cat /etc/libvirt/qemu/sles11.xml cat /etc/libvirt/qemu/networks/default.xml <network> <name>default</name> [...] <bridge name="br0" /> [...]</network>

KVM – Selected Image Formats

Name Compression Snapshot Encryption Deltas

qcow2 X X X Xvmdk X

KVM – Converting, Compressing and Encrypting Images• qemu-img convert -O qcow2 \ /var/lib/kvm/images/sles11_raw_disk1.img \ /var/lib/kvm/images/sles11_qcow2_disk1.img

• qemu-img convert -c -O qcow2 \ /var/lib/kvm/images/sles11_qcow2_disk1.img \ /var/lib/kvm/images/sles11_qcow2_compr_disk1.img

• qemu-img convert -e -O qcow2 \ /var/lib/kvm/images/sles11_qcow2_compr_disk1.img \ /var/lib/kvm/images/sles11_qcow2_compr_encr_disk1.img

Virt-Manager – Hardware Configuration

KVM – Snapshots

• qemu-img snapshot -l image.img

• qemu-img snapshot -a snapshot image.img

• qemu-img snapshot -c snapshot image.img

• qemu-img snapshot -d snapshot image.img

KVM – Live Migration

• CLI:

qemu-kvm -incoming tcp:0:4444(qemu) migrate -d tcp:192.168.3.34:4444

• Via libvirt and virt-manger instances

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