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Virtualization Guide
  1. Preface
  2. I Introduction
    1. 1 Virtualization technology
    2. 2 Virtualization scenarios
    3. 3 Introduction to Xen virtualization
    4. 4 Introduction to KVM virtualization
    5. 5 Virtualization tools
    6. 6 Installation of virtualization components
  3. II Managing virtual machines with libvirt
    1. 7 libvirt daemons
    2. 8 Preparing the VM Host Server
    3. 9 Guest installation
    4. 10 Basic VM Guest management
    5. 11 Connecting and authorizing
    6. 12 Advanced storage topics
    7. 13 Configuring virtual machines with Virtual Machine Manager
    8. 14 Configuring virtual machines with virsh
    9. 15 Xen to KVM migration guide
  4. III Hypervisor-independent features
    1. 16 Disk cache modes
    2. 17 VM Guest clock settings
    3. 18 libguestfs
    4. 19 QEMU guest agent
    5. 20 Software TPM emulator
    6. 21 Creating crash dumps of a VM Guest
  5. IV Managing virtual machines with Xen
    1. 22 Setting up a virtual machine host
    2. 23 Virtual networking
    3. 24 Managing a virtualization environment
    4. 25 Block devices in Xen
    5. 26 Virtualization: configuration options and settings
    6. 27 Administrative tasks
    7. 28 XenStore: configuration database shared between domains
    8. 29 Xen as a high-availability virtualization host
    9. 30 Xen: converting a paravirtual (PV) guest into a fully virtual (FV/HVM) guest
  6. V Managing virtual machines with QEMU
    1. 31 QEMU overview
    2. 32 Setting up a KVM VM Host Server
    3. 33 Guest installation
    4. 34 Running virtual machines with qemu-system-ARCH
    5. 35 Virtual machine administration using QEMU monitor
  7. VI Troubleshooting
    1. 36 Integrated help and package documentation
    2. 37 Gathering system information and logs
  8. Glossary
  9. A Configuring GPU Pass-Through for NVIDIA cards
  10. B GNU licenses
Applies to openSUSE Leap 15.5

2 Virtualization scenarios Edit source


Virtualization provides several useful capabilities to your organization, for example:

  • more efficient hardware usage

  • support for legacy software

  • operating system isolation

  • live migration

  • disaster recovery

  • load balancing

2.1 Server consolidation Edit source

Many servers can be replaced by one big physical server, so that hardware is consolidated, and guest operating systems are converted to virtual machines. This also supports running legacy software on new hardware.

  • Better usage of resources that were not running at 100%

  • Fewer server locations needed

  • More efficient use of computer resources: multiple workloads on the same server

  • Simplification of data center infrastructure

  • Simplifies moving workloads to other hosts, avoiding service downtime

  • Faster and agile virtual machine provisioning

  • Multiple guest operating systems can run on a single host


Server consolidation requires special attention to the following points:

  • Maintenance windows should be carefully planned

  • Storage is key: it must be able to support migration and growing disk usage

  • You must verify that your servers can support the additional workloads

2.2 Isolation Edit source

Guest operating systems are fully isolated from the host running them. Therefore, if there are problems inside virtual machines, the host is not harmed. Also, problems inside one VM do not affect other VMs. No data is shared between VMs.

  • UEFI Secure Boot can be used for VMs.

  • KSM should be avoided. For more details on KSM, refer to KSM.

  • Individual CPU cores can be assigned to VMs.

  • Hyper-threading (HT) should be disabled to avoid potential security issues.

  • VM should not share network, storage, or network hardware.

  • Use of advanced hypervisor features such as PCI pass-through or NUMA adversely affects VM migration capabilities.

  • Use of paravirtualization and virtio drivers improves VM performance and efficiency.

AMD provides specific features regarding the security of virtualization.

2.3 Disaster recovery Edit source

The hypervisor can make snapshots of VMs, enabling restoration to a known good state, or to any desired earlier state. Since Virtualized OSes are less dependent on hardware configuration than those running directly on bare metal, these snapshots can be restored onto different server hardware so long as it is running the same hypervisor.

2.4 Dynamic load balancing Edit source

Live migration provides a simple way to load-balance your services across your infrastructure, by moving VMs from busy hosts to those with spare capacity, on demand.

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