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9.3. Explanation of Settings and Controls in the New Pool and Edit Pool Windows

9.3.1. New Pool and Edit Pool General Settings Explained

The following table details the information required on the General tab of the New Pool and Edit Pool windows that are specific to virtual machine pools. All other settings are identical to those in the New Virtual Machine window.

Table 9.1. General settings

Field NameDescription

Template

The template and template sub-version on which the virtual machine pool is based. If you create a pool based on the latest sub-version of a template, all virtual machines in the pool, when rebooted, will automatically receive the latest template version. For more information on configuring templates for virtual machines see Virtual Machine General Settings Explained and Explanation of Settings in the New Template and Edit Template Windows in the Virtual Machine Management Guide.

Description

A meaningful description of the virtual machine pool.

Comment

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

Prestarted VMs

Allows you to specify the number of virtual machines in the virtual machine pool that will be started before they are taken and kept in that state to be taken by users. The value of this field must be between 0 and the total number of virtual machines in the virtual machine pool.

Number of VMs/Increase number of VMs in pool by

Allows you to specify the number of virtual machines to be created and made available in the virtual machine pool. In the edit window it allows you to increase the number of virtual machines in the virtual machine pool by the specified number. By default, the maximum number of virtual machines you can create in a pool is 1000. This value can be configured using the MaxVmsInPool key of the engine-config command.

Maximum number of VMs per user

Allows you to specify the maximum number of virtual machines a single user can take from the virtual machine pool at any one time. The value of this field must be between 1 and 32,767.

Delete Protection

Allows you to prevent the virtual machines in the pool from being deleted.

9.3.2. New Pool and Edit Pool Type Settings Explained

The following table details the information required on the Type tab of the New Pool and Edit Pool windows.

Table 9.2. Type settings

Field NameDescription

Pool Type

This drop-down menu allows you to specify the type of the virtual machine pool. The following options are available:

  • Automatic: After a user finishes using a virtual machine taken from a virtual machine pool, that virtual machine is automatically returned to the virtual machine pool.
  • Manual: After a user finishes using a virtual machine taken from a virtual machine pool, that virtual machine is only returned to the virtual machine pool when an administrator manually returns the virtual machine.

Stateful Pool

Specify whether the state of virtual machines in the pool is preserved when a virtual machine is passed to a different user. This means that changes made by a previous user will persist on the virtual machine.

9.3.3. New Pool and Edit Pool Console Settings Explained

The following table details the information required on the Console tab of the New Pool or Edit Pool window that is specific to virtual machine pools. All other settings are identical to those in the New Virtual Machine and Edit Virtual Machine windows.

Table 9.3. Console settings

Field NameDescription

Override SPICE proxy

Select this check box to enable overriding the SPICE proxy defined in global configuration. This feature is useful in a case where the user (who is, for example, connecting via the VM Portal) is outside of the network where the hosts reside.

Overridden SPICE proxy address

The proxy by which the SPICE client connects to virtual machines. This proxy overrides both the global SPICE proxy defined for the Red Hat Virtualization environment and the SPICE proxy defined for the cluster to which the virtual machine pool belongs, if any. The address must be in the following format:

protocol://host:port

9.3.4. Virtual Machine Pool Host Settings Explained

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

Table 9.4. Virtual Machine Pool: 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 converging 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 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 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.

9.3.5. New Pool and Edit Pool Resource Allocation Settings Explained

The following table details the information required on the Resource Allocation tab of the New Pool and Edit Pool windows that are specific to virtual machine pools. All other settings are identical to those in the New Virtual Machine window. See Virtual Machine Resource Allocation Settings Explained in the Virtual Machine Management Guide for more information.

Table 9.5. Resource Allocation settings

Field NameSub-elementDescription

Disk Allocation

Auto select target

Select this check box to automatically select the storage domain that has the most free space. The Target and Disk Profile fields are disabled.

 

Format

This field is read-only and always displays QCOW2 unless the storage domain type is OpenStack Volume (Cinder), in which case the format is Raw.