10.5. Explanation of Settings and Controls in the New Virtual Machine and Edit Virtual Machine Windows

⁠10.5.1. 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.

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Table 10.4. Virtual Machine: General Settings

Field Name	Description
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.
Based on Template	The template on which the virtual machine can be 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.
Template Sub Version	The version of the template on which the virtual machine can be based. This field is set to the most recent version for the given template by default. If no versions other than the base template are available, this field is set to `base template` by default. Each version is marked by a number in brackets that indicates the relative order of the versions, with higher numbers indicating more recent versions.
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 two options: Server, and Desktop; 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. In contrast, virtual machines optimized to act as desktop machines do have a sound card, use an image (thin allocation), and are stateless.
Name	The name of the virtual machine. Names 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.
Description	A meaningful description of the new virtual machine.
Comment	A field for adding plain text human-readable comments regarding the virtual machine.
Stateless	Select this check box to run the virtual machine in stateless mode. This mode is used primarily for desktop VMs. Running a stateless desktop or server creates a new COW layer on the VM hard disk image where new and changed data is stored. Shutting down the stateless VM deletes the new COW layer, which returns the VM to its original state. Stateless VMs 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 VMs which require a long time to establish a SPICE connection; for example, VMs 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.

At the bottom of the General tab is a drop-down box that allows you to assign network interfaces to the new virtual machine. Use the plus and minus buttons to add or remove additional network interfaces.

⁠10.5.2. Virtual Machine System Settings Explained

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

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Table 10.5. Virtual Machine: System Settings

Field Name	Description
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 guest memory is 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. Do not assign more cores to a virtual machine than are present on the physical host.
Cores per Virtual Socket	The number of cores assigned to each virtual socket.
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.
Time Zone	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 checkbox 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.

⁠10.5.3. 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.

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Table 10.6. Virtual Machine: Initial Run Settings

Field Name	Operating System	Description
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 Enterprise Virtualization Manager is installed and alter the fields as required.

⁠10.5.4. 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.

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Table 10.7. Virtual Machine: Console Settings

Field Name	Description
Protocol	Defines which display protocol to use. SPICE is the recommended protocol for Linux and Windows virtual machines. Optionally, select VNC for Linux virtual machines. A VNC client is required to connect to a virtual machine using the VNC protocol.
VNC Keyboard Layout	Defines the keyboard layout for the virtual machine. This option is only available when using the VNC protocol.
USB Support	Defines whether USB devices can be used on the virtual machine. This option is only available for virtual machines using the SPICE protocol. Select either: Disabled - Does not allow USB redirection from the client machine to the virtual machine. Legacy - Enables the SPICE USB redirection policy used in Red Hat Enterprise Virtualization 3.0. This option can only be used on Windows virtual machines, and will not be supported in future versions of Red Hat Enterprise Virtualization. Native - 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. This option can only be used if the virtual machine's cluster compatibility version is set to 3.1 or higher.
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 Enterprise Virtualization virtual machines. Tick or untick the check box to activate and deactivate Smart card authentication for individual virtual machines.
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.
VirtIO Console Device Enabled	The VirtIO console device is a console over VirtIO transport for communication between the host user space and guest user space. It has two parts: device emulation in QEMU that presents a virtio-pci device to the guest, and a guest driver that presents a character device interface to user space applications. Tick the check box to attach a VirtIO console device to your virtual machine.
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.

⁠10.5.5. 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.

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Table 10.8. Virtual Machine: Host Settings

Field Name	Description
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 - 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 from the drop-down list of available hosts.
Migration Options	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. The Use custom migration downtime 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. The VDSM default value is 0. The Pass-Through Host CPU 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	Defines options for virtual NUMA nodes. These options are only available if the virtual machine's host has at least two NUMA nodes. NUMA Node Count allows you to specify 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 defines the method used to allocate memory. Choose one of the following from the drop-down list: 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. The NUMA Pinning button 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.

⁠10.5.6. 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.

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Table 10.9. Virtual Machine: High Availability Settings

Field Name	Description
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.
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.

⁠10.5.7. 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.

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Table 10.10. Virtual Machine: Resource Allocation Settings

Field Name	Sub-element	Description
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. This option is not supported if the virtual machine's cluster compatibility version is set to 3.0. 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
Memory Allocation		The amount of physical memory guaranteed for this virtual machine.
Storage Allocation		The Template Provisioning 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.
	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.
	VirtIO-SCSI Enabled	Allows users to enable or disable the use of VirtIO-SCSI on the virtual machines.

⁠10.5.8. 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

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Table 10.11. Virtual Machine: Boot Options Settings

Field Name	Description
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.

⁠10.5.9. 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.

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Table 10.12. Virtual Machine: Random Generator

Field Name	Description
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/random source - The Linux-provided random number generator. /dev/hwrng source - An external hardware generator.

Important

This feature is only supported with a host running Red Hat Enterprise Linux 6.6 and later or Red Hat Enterprise Linux 7.0 and later.

⁠10.5.10. 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.

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Table 10.13. Virtual Machine: Custom Properties Settings

Field Name	Description	Recommendations 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.	For Red Hat Enterprise Virtualization 3.1, 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.