Appendix A. Reference: Settings in Administration Portal and VM Portal Windows

A.1. Explanation of Settings in the New Virtual Machine and Edit Virtual Machine Windows

A.1.1. Virtual Machine General Settings Explained

The following table details the options available on the General tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.1. Virtual Machine: General Settings

Field NameDescription

Cluster

The name of the host cluster to which the virtual machine is attached. Virtual machines are hosted on any physical machine in that cluster in accordance with policy rules.

Template

The template on which the virtual machine is based. This field is set to Blank by default, which allows you to create a virtual machine on which an operating system has not yet been installed. Templates are displayed as Name | Sub-version name (Sub-version number). Each new version is displayed with a number in brackets that indicates the relative order of the version, with a higher number indicating a more recent version.

The version name is displayed as base version if it is the root template of the template version chain.

When the virtual machine is stateless, there is an option to select the latest version of the template. This option means that anytime a new version of this template is created, the virtual machine is automatically recreated on restart based on the latest template.

Operating System

The operating system. Valid values include a range of Red Hat Enterprise Linux and Windows variants.

Instance Type

The instance type on which the virtual machine’s hardware configuration can be based. This field is set to Custom by default, which means the virtual machine is not connected to an instance type. The other options available from this drop down menu are Large, Medium, Small, Tiny, XLarge, and any custom instance types that the Administrator has created.

Other settings that have a chain link icon next to them are pre-filled by the selected instance type. If one of these values is changed, the virtual machine will be detached from the instance type and the chain icon will appear broken. However, if the changed setting is restored to its original value, the virtual machine will be reattached to the instance type and the links in the chain icon will rejoin.

Optimized for

The type of system for which the virtual machine is to be optimized. There are three options: Server, Desktop, and High Performance; by default, the field is set to Server. Virtual machines optimized to act as servers have no sound card, use a cloned disk image, and are not stateless. Virtual machines optimized to act as desktop machines do have a sound card, use an image (thin allocation), and are stateless. Virtual machines optimized for high performance have a number of configuration changes. See Section 4.10, “Configuring High Performance Virtual Machines, Templates, and Pools”.

Name

The name of the virtual machine. The name must be a unique name within the data center and must not contain any spaces, and must contain at least one character from A-Z or 0-9. The maximum length of a virtual machine name is 255 characters. The name can be reused in different data centers in the environment.

VM ID

The virtual machine ID. The virtual machine’s creator can set a custom ID for that virtual machine. The custom ID must contain only numbers, in the format, 00000000-0000-0000-0000-00000000.

If no ID is specified during creation a UUID will be automatically assigned. For both custom and automatically-generated IDs, changes are not possible after virtual machine creation.

Description

A meaningful description of the new virtual machine.

Comment

A field for adding plain text human-readable comments regarding the virtual machine.

Affinity Labels

Add or remove a selected Affinity Label.

Stateless

Select this check box to run the virtual machine in stateless mode. This mode is used primarily for desktop virtual machines. Running a stateless desktop or server creates a new COW layer on the virtual machine hard disk image where new and changed data is stored. Shutting down the stateless virtual machine deletes the new COW layer which includes all data and configuration changes, and returns the virtual machine to its original state. Stateless virtual machines are useful when creating machines that need to be used for a short time, or by temporary staff.

Start in Pause Mode

Select this check box to always start the virtual machine in pause mode. This option is suitable for virtual machines which require a long time to establish a SPICE connection; for example, virtual machines in remote locations.

Delete Protection

Select this check box to make it impossible to delete the virtual machine. It is only possible to delete the virtual machine if this check box is not selected.

Instance Images

Click Attach to attach a floating disk to the virtual machine, or click Create to add a new virtual disk. Use the plus and minus buttons to add or remove additional virtual disks.

Click Edit to change the configuration of a virtual disk that has already been attached or created.

Instantiate VM network interfaces by picking a vNIC profile.

Add a network interface to the virtual machine by selecting a vNIC profile from the nic1 drop-down list. Use the plus and minus buttons to add or remove additional network interfaces.

A.1.2. Virtual Machine System Settings Explained

CPU Considerations

  • For non-CPU-intensive workloads, you can run virtual machines with a total number of processor cores greater than the number of cores in the host. Doing so enables the following:

    • You can run a greater number of virtual machines, which reduces hardware requirements.
    • You can configure virtual machines with CPU topologies that are otherwise not possible, such as when the number of virtual cores is between the number of host cores and the number of host threads.
  • For best performance, and especially for CPU-intensive workloads, you should use the same topology in the virtual machine as in the host, so the host and the virtual machine expect the same cache usage. When the host has hyperthreading enabled, QEMU treats the host’s hyperthreads as cores, so the virtual machine is not aware that it is running on a single core with multiple threads. This behavior might impact the performance of a virtual machine, because a virtual core that actually corresponds to a hyperthread in the host core might share a single cache with another hyperthread in the same host core, while the virtual machine treats it as a separate core.

The following table details the options available on the System tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.2. Virtual Machine: System Settings

Field NameDescription

Memory Size

The amount of memory assigned to the virtual machine. When allocating memory, consider the processing and storage needs of the applications that are intended to run on the virtual machine.

Maximum Memory

The maximum amount of memory that can be assigned to the virtual machine. Maximum guest memory is also constrained by the selected guest architecture and the cluster compatibility level.

Total Virtual CPUs

The processing power allocated to the virtual machine as CPU Cores. For high performance, do not assign more cores to a virtual machine than are present on the physical host.

Virtual Sockets

The number of CPU sockets for the virtual machine. Do not assign more sockets to a virtual machine than are present on the physical host.

Cores per Virtual Socket

The number of cores assigned to each virtual socket.

Threads per Core

The number of threads assigned to each core. Increasing the value enables simultaneous multi-threading (SMT). IBM POWER8 supports up to 8 threads per core. For x86 and x86_64 (Intel and AMD) CPU types, the recommended value is 1, unless you want to replicate the exact host topology, which you can do using CPU pinning. For more information, see Section 4.10.2.2, “Pinning CPUs”.

Custom Emulated Machine

This option allows you to specify the machine type. If changed, the virtual machine will only run on hosts that support this machine type. Defaults to the cluster’s default machine type.

Custom CPU Type

This option allows you to specify a CPU type. If changed, the virtual machine will only run on hosts that support this CPU type. Defaults to the cluster’s default CPU type.

Custom Compatibility Version

The compatibility version determines which features are supported by the cluster, as well as, the values of some properties and the emulated machine type. By default, the virtual machine is configured to run in the same compatibility mode as the cluster as the default is inherited from the cluster. In some situations the default compatibility mode needs to be changed. An example of this is if the cluster has been updated to a later compatibility version but the virtual machines have not been restarted. These virtual machines can be set to use a custom compatibility mode that is older than that of the cluster. See Changing the Cluster Compatibility Version in the Administration Guide for more information.

Hardware Clock Time Offset

This option sets the time zone offset of the guest hardware clock. For Windows, this should correspond to the time zone set in the guest. Most default Linux installations expect the hardware clock to be GMT+00:00.

Provide custom serial number policy

This check box allows you to specify a serial number for the virtual machine. Select either:

  • Host ID: Sets the host’s UUID as the virtual machine’s serial number.
  • Vm ID: Sets the virtual machine’s UUID as its serial number.
  • Custom serial number: Allows you to specify a custom serial number.

A.1.3. Virtual Machine Initial Run Settings Explained

The following table details the options available on the Initial Run tab of the New Virtual Machine and Edit Virtual Machine windows. The settings in this table are only visible if the Use Cloud-Init/Sysprep check box is selected, and certain options are only visible when either a Linux-based or Windows-based option has been selected in the Operating System list in the General tab, as outlined below.

Table A.3. Virtual Machine: Initial Run Settings

Field NameOperating SystemDescription

Use Cloud-Init/Sysprep

Linux, Windows

This check box toggles whether Cloud-Init or Sysprep will be used to initialize the virtual machine.

VM Hostname

Linux, Windows

The host name of the virtual machine.

Domain

Windows

The Active Directory domain to which the virtual machine belongs.

Organization Name

Windows

The name of the organization to which the virtual machine belongs. This option corresponds to the text field for setting the organization name displayed when a machine running Windows is started for the first time.

Active Directory OU

Windows

The organizational unit in the Active Directory domain to which the virtual machine belongs.

Configure Time Zone

Linux, Windows

The time zone for the virtual machine. Select this check box and select a time zone from the Time Zone list.

Admin Password

Windows

The administrative user password for the virtual machine. Click the disclosure arrow to display the settings for this option.

  • Use already configured password: This check box is automatically selected after you specify an initial administrative user password. You must clear this check box to enable the Admin Password and Verify Admin Password fields and specify a new password.
  • Admin Password: The administrative user password for the virtual machine. Enter the password in this text field and the Verify Admin Password text field to verify the password.

Authentication

Linux

The authentication details for the virtual machine. Click the disclosure arrow to display the settings for this option.

  • Use already configured password: This check box is automatically selected after you specify an initial root password. You must clear this check box to enable the Password and Verify Password fields and specify a new password.
  • Password: The root password for the virtual machine. Enter the password in this text field and the Verify Password text field to verify the password.
  • SSH Authorized Keys: SSH keys to be added to the authorized keys file of the virtual machine. You can specify multiple SSH keys by entering each SSH key on a new line.
  • Regenerate SSH Keys: Regenerates SSH keys for the virtual machine.

Custom Locale

Windows

Custom locale options for the virtual machine. Locales must be in a format such as en-US. Click the disclosure arrow to display the settings for this option.

  • Input Locale: The locale for user input.
  • UI Language: The language used for user interface elements such as buttons and menus.
  • System Locale: The locale for the overall system.
  • User Locale: The locale for users.

Networks

Linux

Network-related settings for the virtual machine. Click the disclosure arrow to display the settings for this option.

  • DNS Servers: The DNS servers to be used by the virtual machine.
  • DNS Search Domains: The DNS search domains to be used by the virtual machine.
  • Network: Configures network interfaces for the virtual machine. Select this check box and click + or - to add or remove network interfaces to or from the virtual machine. When you click +, a set of fields becomes visible that can specify whether to use DHCP, and configure an IP address, netmask, and gateway, and specify whether the network interface will start on boot.

Custom Script

Linux

Custom scripts that will be run on the virtual machine when it starts. The scripts entered in this field are custom YAML sections that are added to those produced by the Manager, and allow you to automate tasks such as creating users and files, configuring yum repositories and running commands. For more information on the format of scripts that can be entered in this field, see the Custom Script documentation.

Sysprep

Windows

A custom Sysprep definition. The definition must be in the format of a complete unattended installation answer file. You can copy and paste the default answer files in the /usr/share/ovirt-engine/conf/sysprep/ directory on the machine on which the Red Hat Virtualization Manager is installed and alter the fields as required. See Chapter 7, Templates for more information.

A.1.4. Virtual Machine Console Settings Explained

The following table details the options available on the Console tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.4. Virtual Machine: Console Settings

Field NameDescription

Graphical Console Section

 

Headless Mode

Select this check box if you do not a require a graphical console for the virtual machine.

When selected, all other fields in the Graphical Console section are disabled. In the VM Portal, the Console icon in the virtual machine’s details view is also disabled.

Important

See Section 4.9, “Configuring Headless Virtual Machines” for more details and prerequisites for using headless mode.

Video Type

Defines the graphics device. QXL is the default and supports both graphic protocols. VGA and CIRRUS support only the VNC protocol.

Graphics protocol

Defines which display protocol to use. SPICE is the default protocol. VNC is an alternative option. To allow both protocols select SPICE + VNC.

VNC Keyboard Layout

Defines the keyboard layout for the virtual machine. This option is only available when using the VNC protocol.

USB Support

Defines SPICE USB redirection. This option is only available for virtual machines using the SPICE protocol. Select either:

  • Disabled - USB controller devices are added according to the devices.usb.controller value in the osinfo-defaults.properties configuration file. The default for all x86 and x86_64 operating systems is piix3-uhci. For ppc64 systems, the default is nec-xhci.
  • Enabled - Enables native KVM/SPICE USB redirection for Linux and Windows virtual machines. Virtual machines do not require any in-guest agents or drivers for native USB.

Console Disconnect Action

Defines what happens when the console is disconnected. This is only relevant with SPICE and VNC console connections. This setting can be changed while the virtual machine is running but will not take effect until a new console connection is established. Select either:

  • No action - No action is taken.
  • Lock screen - This is the default option. For all Linux machines and for Windows desktops this locks the currently active user session. For Windows servers, this locks the desktop and the currently active user.
  • Logout user - For all Linux machines and Windows desktops, this logs out the currently active user session. For Windows servers, the desktop and the currently active user are logged out.
  • Shutdown virtual machine - Initiates a graceful virtual machine shutdown.
  • Reboot virtual machine - Initiates a graceful virtual machine reboot.

Monitors

The number of monitors for the virtual machine. This option is only available for virtual desktops using the SPICE display protocol. You can choose 1, 2 or 4. Note that multiple monitors are not supported for Windows 8 and Windows Server 2012 virtual machines.

Smartcard Enabled

Smart cards are an external hardware security feature, most commonly seen in credit cards, but also used by many businesses as authentication tokens. Smart cards can be used to protect Red Hat Virtualization virtual machines. Tick or untick the check box to activate and deactivate Smart card authentication for individual virtual machines.

Single Sign On method

Enabling Single Sign On allows users to sign into the guest operating system when connecting to a virtual machine from the VM Portal using the Guest Agent.

  • Disable Single Sign On - Select this option if you do not want the Guest Agent to attempt to sign into the virtual machine.
  • Use Guest Agent - Enables Single Sign On to allow the Guest Agent to sign you into the virtual machine.

Disable strict user checking

Click the Advanced Parameters arrow and select the check box to use this option. With this option selected, the virtual machine does not need to be rebooted when a different user connects to it.

By default, strict checking is enabled so that only one user can connect to the console of a virtual machine. No other user is able to open a console to the same virtual machine until it has been rebooted. The exception is that a SuperUser can connect at any time and replace a existing connection. When a SuperUser has connected, no normal user can connect again until the virtual machine is rebooted.

Disable strict checking with caution, because you can expose the previous user’s session to the new user.

Soundcard Enabled

A sound card device is not necessary for all virtual machine use cases. If it is for yours, enable a sound card here.

Enable SPICE file transfer

Defines whether a user is able to drag and drop files from an external host into the virtual machine’s SPICE console. This option is only available for virtual machines using the SPICE protocol. This check box is selected by default.

Enable SPICE clipboard copy and paste

Defines whether a user is able to copy and paste content from an external host into the virtual machine’s SPICE console. This option is only available for virtual machines using the SPICE protocol. This check box is selected by default.

Serial Console Section

 

Enable VirtIO serial console

The VirtIO serial console is emulated through VirtIO channels, using SSH and key pairs, and allows you to access a virtual machine’s serial console directly from a client machine’s command line, instead of opening a console from the Administration Portal or the VM Portal. The serial console requires direct access to the Manager, since the Manager acts as a proxy for the connection, provides information about virtual machine placement, and stores the authentication keys. Select the check box to enable the VirtIO console on the virtual machine.

A.1.5. Virtual Machine Host Settings Explained

The following table details the options available on the Host tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.5. Virtual Machine: Host Settings

Field NameSub-elementDescription

Start Running On

 

Defines the preferred host on which the virtual machine is to run. Select either:

  • Any Host in Cluster - The virtual machine can start and run on any available host in the cluster.
  • Specific Host(s) - The virtual machine will start running on a particular host in the cluster. However, the Manager or an administrator can migrate the virtual machine to a different host in the cluster depending on the migration and high-availability settings of the virtual machine. Select the specific host or group of hosts from the list of available hosts.

Migration Options

Migration mode

Defines options to run and migrate the virtual machine. If the options here are not used, the virtual machine will run or migrate according to its cluster’s policy.

  • Allow manual and automatic migration - The virtual machine can be automatically migrated from one host to another in accordance with the status of the environment, or manually by an administrator.
  • Allow manual migration only - The virtual machine can only be migrated from one host to another manually by an administrator.
  • Do not allow migration - The virtual machine cannot be migrated, either automatically or manually.
 

Use custom migration policy

Defines the migration convergence policy. If the check box is left unselected, the host determines the policy.

  • Legacy - Legacy behavior of 3.6 version. Overrides in vdsm.conf are still applied. The guest agent hook mechanism is disabled.
  • Minimal downtime - Allows the virtual machine to migrate in typical situations. Virtual machines should not experience any significant downtime. The migration will be aborted if virtual machine migration does not converge after a long time (dependent on QEMU iterations, with a maximum of 500 milliseconds). The guest agent hook mechanism is enabled.
  • Suspend workload if needed - Allows the virtual machine to migrate in most situations, including when the virtual machine is running a heavy workload. Virtual machines may experience a more significant downtime. The migration may still be aborted for extreme workloads. The guest agent hook mechanism is enabled.
 

Use custom migration downtime

This check box allows you to specify the maximum number of milliseconds the virtual machine can be down during live migration. Configure different maximum downtimes for each virtual machine according to its workload and SLA requirements. Enter 0 to use the VDSM default value.

 

Auto Converge migrations

Only activated with the Legacy migration policy. Allows you to set whether auto-convergence is used during live migration of the virtual machine. Large virtual machines with high workloads can dirty memory more quickly than the transfer rate achieved during live migration, and prevent the migration from converging. Auto-convergence capabilities in QEMU allow you to force convergence of virtual machine migrations. QEMU automatically detects a lack of convergence and triggers a throttle-down of the vCPUs on the virtual machine. Auto-convergence is disabled globally by default.

  • Select Inherit from cluster setting to use the auto-convergence setting that is set at the cluster level. This option is selected by default.
  • Select Auto Converge to override the cluster setting or global setting and allow auto-convergence for the virtual machine.
  • Select Don’t Auto Converge to override the cluster setting or global setting and prevent auto-convergence for the virtual machine.
 

Enable migration compression

Only activated with the Legacy migration policy. The option allows you to set whether migration compression is used during live migration of the virtual machine. This feature uses Xor Binary Zero Run-Length-Encoding to reduce virtual machine downtime and total live migration time for virtual machines running memory write-intensive workloads or for any application with a sparse memory update pattern. Migration compression is disabled globally by default.

  • Select Inherit from cluster setting to use the compression setting that is set at the cluster level. This option is selected by default.
  • Select Compress to override the cluster setting or global setting and allow compression for the virtual machine.
  • Select Don’t compress to override the cluster setting or global setting and prevent compression for the virtual machine.
 

Pass-Through Host CPU

This check box allows virtual machines to take advantage of the features of the physical CPU of the host on which they are situated. This option can only be enabled when Do not allow migration is selected.

Configure NUMA

NUMA Node Count

The number of virtual NUMA nodes to assign to the virtual machine. If the Tune Mode is Preferred, this value must be set to 1.

 

Tune Mode

The method used to allocate memory.

  • Strict: Memory allocation will fail if the memory cannot be allocated on the target node.
  • Preferred: Memory is allocated from a single preferred node. If sufficient memory is not available, memory can be allocated from other nodes.
  • Interleave: Memory is allocated across nodes in a round-robin algorithm.
 

NUMA Pinning

Opens the NUMA Topology window. This window shows the host’s total CPUs, memory, and NUMA nodes, and the virtual machine’s virtual NUMA nodes. Pin virtual NUMA nodes to host NUMA nodes by clicking and dragging each vNUMA from the box on the right to a NUMA node on the left.

A.1.6. Virtual Machine High Availability Settings Explained

The following table details the options available on the High Availability tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.6. Virtual Machine: High Availability Settings

Field NameDescription

Highly Available

Select this check box if the virtual machine is to be highly available. For example, in cases of host maintenance, all virtual machines are automatically live migrated to another host. If the host crashed and is in a non-responsive state, only virtual machines with high availability are restarted on another host. If the host is manually shut down by the system administrator, the virtual machine is not automatically live migrated to another host.

Note that this option is unavailable if the Migration Options setting in the Hosts tab is set to either Allow manual migration only or Do not allow migration. For a virtual machine to be highly available, it must be possible for the Manager to migrate the virtual machine to other available hosts as necessary.

Target Storage Domain for VM Lease

Select the storage domain to hold a virtual machine lease, or select No VM Lease to disable the functionality. When a storage domain is selected, it will hold a virtual machine lease on a special volume that allows the virtual machine to be started on another host if the original host loses power or becomes unresponsive.

This functionality is only available on storage domain V4 or later.

Note

If you define a lease, the only Resume Behavior available is KILL.

Resume Behavior

Defines the desired behavior of a virtual machine that is paused due to storage I/O errors, once a connection with the storage is reestablished. You can define the desired resume behavior even if the virtual machine is not highly available.

The following options are available:

  • AUTO_RESUME - The virtual machine is automatically resumed, without requiring user intervention. This is recommended for virtual machines that are not highly available and that do not require user intervention after being in the paused state.
  • LEAVE_PAUSED - The virtual machine remains in pause mode until it is manually resumed or restarted.
  • KILL - The virtual machine is automatically resumed if the I/O error is remedied within 80 seconds. However, if more than 80 seconds pass, the virtual machine is ungracefully shut down. This is recommended for highly available virtual machines, to allow the Manager to restart them on another host that is not experiencing the storage I/O error.

    KILL is the only option available when using virtual machine leases.

Priority for Run/Migration queue

Sets the priority level for the virtual machine to be migrated or restarted on another host.

Watchdog

Allows users to attach a watchdog card to a virtual machine. A watchdog is a timer that is used to automatically detect and recover from failures. Once set, a watchdog timer continually counts down to zero while the system is in operation, and is periodically restarted by the system to prevent it from reaching zero. If the timer reaches zero, it signifies that the system has been unable to reset the timer and is therefore experiencing a failure. Corrective actions are then taken to address the failure. This functionality is especially useful for servers that demand high availability.

Watchdog Model: The model of watchdog card to assign to the virtual machine. At current, the only supported model is i6300esb.

Watchdog Action: The action to take if the watchdog timer reaches zero. The following actions are available:

  • none - No action is taken. However, the watchdog event is recorded in the audit log.
  • reset - The virtual machine is reset and the Manager is notified of the reset action.
  • poweroff - The virtual machine is immediately shut down.
  • dump - A dump is performed and the virtual machine is paused.
  • pause - The virtual machine is paused, and can be resumed by users.

A.1.7. Virtual Machine Resource Allocation Settings Explained

The following table details the options available on the Resource Allocation tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.7. Virtual Machine: Resource Allocation Settings

Field NameSub-elementDescription

CPU Allocation

CPU Profile

The CPU profile assigned to the virtual machine. CPU profiles define the maximum amount of processing capability a virtual machine can access on the host on which it runs, expressed as a percent of the total processing capability available to that host. CPU profiles are defined on the cluster level based on quality of service entries created for data centers.

 

CPU Shares

Allows users to set the level of CPU resources a virtual machine can demand relative to other virtual machines.

  • Low - 512
  • Medium - 1024
  • High - 2048
  • Custom - A custom level of CPU shares defined by the user.
 

CPU Pinning topology

Enables the virtual machine’s virtual CPU (vCPU) to run on a specific physical CPU (pCPU) in a specific host. The syntax of CPU pinning is v#p[_v#p], for example:

  • 0#0 - Pins vCPU 0 to pCPU 0.
  • 0#0_1#3 - Pins vCPU 0 to pCPU 0, and pins vCPU 1 to pCPU 3.
  • 1#1-4,^2 - Pins vCPU 1 to one of the pCPUs in the range of 1 to 4, excluding pCPU 2.

In order to pin a virtual machine to a host, you must also select the following on the Host tab:

  • Start Running On: Specific
  • Migration Options: Do not allow migration
  • Pass-Through Host CPU

If CPU pinning is set and you change Start Running On: Specific or Migration Options: Do not allow migration, a CPU pinning topology will be lost window appears when you click OK.

Memory Allocation

Physical Memory Guaranteed

The amount of physical memory guaranteed for this virtual machine. Should be any number between 0 and the defined memory for this virtual machine.

 

Memory Balloon Device Enabled

Enables the memory balloon device for this virtual machine. Enable this setting to allow memory overcommitment in a cluster. Enable this setting for applications that allocate large amounts of memory suddenly but set the guaranteed memory to the same value as the defined memory.Use ballooning for applications and loads that slowly consume memory, occasionally release memory, or stay dormant for long periods of time, such as virtual desktops. See Optimization Settings Explained in the Administration Guide for more information.

IO Threads

IO Threads Enabled

Enables IO threads. Select this check box to improve the speed of disks that have a VirtIO interface by pinning them to a thread separate from the virtual machine’s other functions. Improved disk performance increases a virtual machine’s overall performance. Disks with VirtIO interfaces are pinned to an IO thread using a round-robin algorithm.

Queues

Multi Queues Enabled

Enables multiple queues. This check box is selected by default. It creates up to four queues per vNIC, depending on how many vCPUs are available.

It is possible to define a different number of queues per vNIC by creating a custom property as follows:

engine-config -s "CustomDeviceProperties={type=interface;prop={other-nic-properties;queues=[1-9][0-9]*}}"

where other-nic-properties is a semicolon-separated list of pre-existing NIC custom properties.

Storage Allocation

 

The Storage Allocation option is only available when the virtual machine is created from a template.

 

Thin

Provides optimized usage of storage capacity. Disk space is allocated only as it is required. When selected, the format of the disks will be marked as QCOW2 and you will not be able to change it.

 

Clone

Optimized for the speed of guest read and write operations. All disk space requested in the template is allocated at the time of the clone operation. Possible disk formats are QCOW2 or Raw.

 

VirtIO-SCSI Enabled

Allows users to enable or disable the use of VirtIO-SCSI on the virtual machines.

Disk Allocation

 

The Disk Allocation option is only available when you are creating a virtual machine from a template.

 

Alias

An alias for the virtual disk. By default, the alias is set to the same value as that of the template.

 

Virtual Size

The total amount of disk space that the virtual machine based on the template can use. This value cannot be edited, and is provided for reference only.

 

Format

The format of the virtual disk. The available options are QCOW2 and Raw. When Storage Allocation is Thin, the disk format is QCOW2. When Storage Allocation is Clone, select QCOW2 or Raw.

 

Target

The storage domain on which the virtual disk is stored. By default, the storage domain is set to the same value as that of the template.

 

Disk Profile

The disk profile to assign to the virtual disk. Disk profiles are created based on storage profiles defined in the data centers.

A.1.8. Virtual Machine Boot Options Settings Explained

The following table details the options available on the Boot Options tab of the New Virtual Machine and Edit Virtual Machine windows

Table A.8. Virtual Machine: Boot Options Settings

Field NameDescription

First Device

After installing a new virtual machine, the new virtual machine must go into Boot mode before powering up. Select the first device that the virtual machine must try to boot:

  • Hard Disk
  • CD-ROM
  • Network (PXE)

Second Device

Select the second device for the virtual machine to use to boot if the first device is not available. The first device selected in the previous option does not appear in the options.

Attach CD

If you have selected CD-ROM as a boot device, tick this check box and select a CD-ROM image from the drop-down menu. The images must be available in the ISO domain.

Enable menu to select boot device

Enables a menu to select the boot device. After the virtual machine starts and connects to the console, but before the virtual machine starts booting, a menu displays that allows you to select the boot device. This option should be enabled before the initial boot to allow you to select the required installation media.

A.1.9. Virtual Machine Random Generator Settings Explained

The following table details the options available on the Random Generator tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.9. Virtual Machine: Random Generator Settings

Field NameDescription

Random Generator enabled

Selecting this check box enables a paravirtualized Random Number Generator PCI device (virtio-rng). This device allows entropy to be passed from the host to the virtual machine in order to generate a more sophisticated random number. Note that this check box can only be selected if the RNG device exists on the host and is enabled in the host’s cluster.

Period duration (ms)

Specifies the duration of a period in milliseconds. If omitted, the libvirt default of 1000 milliseconds (1 second) is used. If this field is filled, Bytes per period must be filled also.

Bytes per period

Specifies how many bytes are permitted to be consumed per period.

Device source:

The source of the random number generator. This is automatically selected depending on the source supported by the host’s cluster.

  • /dev/urandom source - The Linux-provided random number generator.
  • /dev/hwrng source - An external hardware generator.

A.1.10. Virtual Machine Custom Properties Settings Explained

The following table details the options available on the Custom Properties tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.10. Virtual Machine: Custom Properties Settings

Field NameDescriptionRecommendations and Limitations

sap_agent

Enables SAP monitoring on the virtual machine. Set to true or false.

-

sndbuf

Enter the size of the buffer for sending the virtual machine’s outgoing data over the socket. Default value is 0.

-

vhost

Disables vhost-net, which is the kernel-based virtio network driver on virtual network interface cards attached to the virtual machine. To disable vhost, the format for this property is LogicalNetworkName: false.

This will explicitly start the virtual machine without the vhost-net setting on the virtual NIC attached to LogicalNetworkName.

vhost-net provides better performance than virtio-net, and if it is present, it is enabled on all virtual machine NICs by default. Disabling this property makes it easier to isolate and diagnose performance issues, or to debug vhost-net errors; for example, if migration fails for virtual machines on which vhost does not exist.

viodiskcache

Caching mode for the virtio disk. writethrough writes data to the cache and the disk in parallel, writeback does not copy modifications from the cache to the disk, and none disables caching. See https://access.redhat.com/solutions/2361311 for more information about the limitations of the viodiskcache custom property.

If viodiskcache is enabled, the virtual machine cannot be live migrated.

Warning

Increasing the value of the sndbuf custom property results in increased occurrences of communication failure between hosts and unresponsive virtual machines.

A.1.11. Virtual Machine Icon Settings Explained

You can add custom icons to virtual machines and templates. Custom icons can help to differentiate virtual machines in the VM Portal. The following table details the options available on the Icon tab of the New Virtual Machine and Edit Virtual Machine windows.

Table A.11. Virtual Machine: Icon Settings

Button NameDescription

Upload

Click this button to select a custom image to use as the virtual machine’s icon. The following limitations apply:

  • Supported formats: jpg, png, gif
  • Maximum size: 24 KB
  • Maximum dimensions: 150px width, 120px height

Use default

Click this button to set the operating system’s default image as the virtual machine’s icon.

A.1.12. Virtual Machine Foreman/Satellite Settings Explained

The following table details the options available on the Foreman/Satellite tab of the New Virtual Machine and Edit Virtual Machine windows

Table A.12. Virtual Machine:Foreman/Satellite Settings

Field NameDescription

Provider

If the virtual machine is running Red Hat Enterprise Linux and the system is configured to work with a Satellite server, select the name of the Satellite from the list. This enables you to use Satellite’s content management feature to display the relevant Errata for this virtual machine. See Section 4.8, “Configuring Red Hat Satellite Errata Management for a Virtual Machine” for more details.