Allocate Dedicated Hosts Launch instances onto a Dedicated Host Launch instances into a host resource group Understand auto-placement and affinity Modify Dedicated Host auto-placement Modify the supported instance types Modify instance tenancy and affinity View Dedicated Hosts Tag Dedicated Hosts Monitor Dedicated Hosts Release Dedicated Hosts Purchase Dedicated Host Reservations View Dedicated Host reservations Tag Dedicated Host Reservations

Work with Dedicated Hosts

To use a Dedicated Host, you first allocate hosts for use in your account. You then launch instances onto the hosts by specifying host tenancy for the instance. You must select a specific host for the instance to launch on to, or you can allow it to launch on to any host that has auto-placement enabled and matches its instance type. When an instance is stopped and restarted, the Host affinity setting determines whether it's restarted on the same, or a different, host.

If you no longer need an On-Demand host, you can stop the instances running on the host, direct them to launch on a different host, and then release the host.

Dedicated Hosts are also integrated with Amazon License Manager. With License Manager, you can create a host resource group, which is a collection of Dedicated Hosts that are managed as a single entity. When creating a host resource group, you specify the host management preferences, such as auto-allocate and auto-release, for the Dedicated Hosts. This allows you to launch instances onto Dedicated Hosts without manually allocating and managing those hosts. For more information, see Host Resource Groups in the Amazon License Manager User Guide.

Contents

Allocate Dedicated Hosts
Launch instances onto a Dedicated Host
Launch instances into a host resource group
Understand auto-placement and affinity
Modify Dedicated Host auto-placement
Modify the supported instance types
Modify instance tenancy and affinity
View Dedicated Hosts
Tag Dedicated Hosts
Monitor Dedicated Hosts
Release Dedicated Hosts
Purchase Dedicated Host Reservations
View Dedicated Host reservations
Tag Dedicated Host Reservations

Allocate Dedicated Hosts

To begin using Dedicated Hosts, you must allocate Dedicated Hosts in your account using the Amazon EC2 console or the command line tools. After you allocate the Dedicated Host, the Dedicated Host capacity is made available in your account immediately and you can start launching instances onto the Dedicated Host.

Support for multiple instance sizes of the same instance family on the same Dedicated Host is available for the following instance families: c5, m5, r5, c5n, r5n, and m5n. Other instance families support only one instance size on the same Dedicated Host.

Due to a hardware limitation with N-type Dedicated Hosts, such as C5n, M5n, and R5n, you cannot mix smaller instance sizes (large, xlarge, and 2xlarge) with larger instance sizes (4xlarge, 9xlarge, 18xlarge, and .metal). If you require smaller and larger instance sizes on N-type hosts at the same time, you must allocate separate hosts for the smaller and larger instance sizes.

You can allocate a Dedicated Host using the following methods.

New console

To allocate a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Dedicated Hosts and then choose Allocate Dedicated Host.
For Instance family, choose the instance family for the Dedicated Host.
Specify whether the Dedicated Host supports multiple instance sizes within the selected instance family, or a specific instance type only. Do one of the following.
- To configure the Dedicated Host to support multiple instance types in the selected instance family, for Support multiple instance types, choose Enable. Enabling this allows you to launch different instance sizes from the same instance family onto the Dedicated Host. For example, if you choose the m5 instance family and choose this option, you can launch m5.xlarge and m5.4xlarge instances onto the Dedicated Host.
- To configure the Dedicated Host to support a single instance type within the selected instance family, clear Support multiple instance types, and then for Instance type, choose the instance type to support. This allows you to launch a single instance type on the Dedicated Host. For example, if you choose this option and specify m5.4xlarge as the supported instance type, you can launch only m5.4xlarge instances onto the Dedicated Host.
For Availability Zone, choose the Availability Zone in which to allocate the Dedicated Host.
To allow the Dedicated Host to accept untargeted instance launches that match its instance type, for Instance auto-placement, choose Enable. For more information about auto-placement, see Understand auto-placement and affinity.
To enable host recovery for the Dedicated Host, for Host recovery, choose Enable. For more information, see Host recovery.
For Quantity, enter the number of Dedicated Hosts to allocate.
(Optional) Choose Add new tag and enter a tag key and a tag value.
Choose Allocate.

Old console

To allocate a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Dedicated Hosts, Allocate Dedicated Host.
For Instance family, choose the instance family for the Dedicated Host.
Specify whether the Dedicated Host supports multiple instance sizes within the selected instance family, or a specific instance type only. Do one of the following.
- To configure the Dedicated Host to support multiple instance types in the selected instance family, select Support multiple instance types. Enabling this allows you to launch different instance sizes from the same instance family onto the Dedicated Host. For example, if you choose the m5 instance family and choose this option, you can launch m5.xlarge and m5.4xlarge instances onto the Dedicated Host. The instance family must be powered by the Nitro System.
- To configure the Dedicated Host to support a single instance type within the selected instance family, clear Support multiple instance types, and then for Instance type, choose the instance type to support. This allows you to launch a single instance type on the Dedicated Host. For example, if you choose this option and specify m5.4xlarge as the supported instance type, you can launch only m5.4xlarge instances onto the Dedicated Host.
For Availability Zone, choose the Availability Zone in which to allocate the Dedicated Host.
To allow the Dedicated Host to accept untargeted instance launches that match its instance type, for Instance auto-placement, choose Enable. For more information about auto-placement, see Understand auto-placement and affinity.
To enable host recovery for the Dedicated Host, for Host recovery choose Enable. For more information, see Host recovery.
For Quantity, enter the number of Dedicated Hosts to allocate.
(Optional) Choose Add Tag and enter a tag key and a tag value.
Choose Allocate host.

Amazon CLI

To allocate a Dedicated Host

Use the allocate-hosts Amazon CLI command. The following command allocates a Dedicated Host that supports multiple instance types from the m5 instance family in us-east-1a Availability Zone. The host also has host recovery enabled and it has auto-placement disabled.


aws ec2 allocate-hosts --instance-family "m5" --availability-zone "us-east-1a" --auto-placement "off" --host-recovery "on" --quantity 1

The following command allocates a Dedicated Host that supports untargeted m4.large instance launches in the eu-west-1a Availability Zone, enables host recovery, and applies a tag with a key of purpose and a value of production.


aws ec2 allocate-hosts --instance-type "m4.large" --availability-zone "eu-west-1a" --auto-placement "on" --host-recovery "on" --quantity 1 --tag-specifications 'ResourceType=dedicated-host,Tags=[{Key=purpose,Value=production}]'

PowerShell

To allocate a Dedicated Host

Use the New-EC2Host Amazon Tools for Windows PowerShell command. The following command allocates a Dedicated Host that supports multiple instance types from the m5 instance family in us-east-1a Availability Zone. The host also has host recovery enabled and it has auto-placement disabled.


PS C:\> New-EC2Host -InstanceFamily m5 -AvailabilityZone us-east-1a -AutoPlacement Off -HostRecovery On -Quantity 1

The following commands allocate a Dedicated Host that supports untargeted m4.large instance launches in the eu-west-1a Availability Zone, enable host recovery, and apply a tag with a key of purpose and a value of production.

The TagSpecification parameter used to tag a Dedicated Host on creation requires an object that specifies the type of resource to be tagged, the tag key, and the tag value. The following commands create the required object.


PS C:\> $tag = @{ Key="purpose"; Value="production" }
PS C:\> $tagspec = new-object Amazon.EC2.Model.TagSpecification
PS C:\> $tagspec.ResourceType = "dedicated-host"
PS C:\> $tagspec.Tags.Add($tag)

The following command allocates the Dedicated Host and applies the tag specified in the $tagspec object.


PS C:\> New-EC2Host -InstanceType m4.large -AvailabilityZone eu-west-1a -AutoPlacement On -HostRecovery On -Quantity 1 -TagSpecification $tagspec

Launch instances onto a Dedicated Host

After you have allocated a Dedicated Host, you can launch instances onto it. You can't launch instances with host tenancy if you do not have active Dedicated Hosts with enough available capacity for the instance type that you are launching.

Note

The instances launched onto Dedicated Hosts can only be launched in a VPC. For more information, see Introduction to VPC.

Before you launch your instances, take note of the limitations. For more information, see Dedicated Hosts restrictions.

You can launch an instance onto a Dedicated Host using the following methods.

Console

To launch an instance onto a specific Dedicated Host from the Dedicated Hosts page

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
Choose Dedicated Hosts in the navigation pane.
On the Dedicated Hosts page, select a host and choose Actions, Launch Instance(s) onto Host.
Select an AMI from the list. SQL Server, SUSE, and RHEL AMIs provided by Amazon EC2 can't be used with Dedicated Hosts.
On the Choose an Instance Type page, select the instance type to launch and then choose Next: Configure Instance Details.

If the Dedicated Host supports a single instance type only, the supported instance type is selected by default and can't be changed.

If the Dedicated Host supports multiple instance types, you must select an instance type within the supported instance family based on the available instance capacity of the Dedicated Host. We recommend that you launch the larger instance sizes first, and then fill the remaining instance capacity with the smaller instance sizes as needed.
On the Configure Instance Details page, configure the instance settings to suit your needs, and then for Affinity, choose one of the following options:
- Off—The instance launches onto the specified host, but it is not guaranteed to restart on the same Dedicated Host if stopped.
- Host—If stopped, the instance always restarts on this specific host.
For more information about Affinity, see Understand auto-placement and affinity.

The Tenancy and Host options are pre-configured based on the host that you selected.
Choose Review and Launch.
On the Review Instance Launch page, choose Launch.
When prompted, select an existing key pair or create a new one, and then choose Launch Instances.

To launch an instance onto a Dedicated Host using the Launch Instance wizard

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Instances, Launch Instance.
Select an AMI from the list. SQL Server, SUSE, and RHEL AMIs provided by Amazon EC2 can't be used with Dedicated Hosts.
Select the type of instance to launch and choose Next: Configure Instance Details.
On the Configure Instance Details page, configure the instance settings to suit your needs, and then configure the following settings, which are specific to a Dedicated Host:
- Tenancy—Choose Dedicated Host - Launch this instance on a Dedicated Host.
- Host—Choose either Use auto-placement to launch the instance on any Dedicated Host that has auto-placement enabled, or select a specific Dedicated Host in the list. The list displays only Dedicated Hosts that support the selected instance type.
- Affinity—Choose one of the following options:
  - Off—The instance launches onto the specified host, but it is not guaranteed to restart on it if stopped.
  - Host—If stopped, the instance always restarts on the specified host.
For more information, see Understand auto-placement and affinity.

If you are unable to see these settings, check that you have selected a VPC in the Network menu.
Choose Review and Launch.
On the Review Instance Launch page, choose Launch.
When prompted, select an existing key pair or create a new one, and then choose Launch Instances.

Amazon CLI

To launch an instance onto a Dedicated Host

Use the run-instances Amazon CLI command and specify the instance affinity, tenancy, and host in the Placement request parameter.

PowerShell

To launch an instance onto a Dedicated Host

Use the New-EC2Instance Amazon Tools for Windows PowerShell command and specify the instance affinity, tenancy, and host in the Placement request parameter.

Launch instances into a host resource group

When you launch an instance into a host resource group that has a Dedicated Host with available instance capacity, Amazon EC2 launches the instance onto that host. If the host resource group does not have a host with available instance capacity, Amazon EC2 automatically allocates a new host in the host resource group, and then launches the instance onto that host. For more information, see Host Resource Groups in the Amazon License Manager User Guide.

Requirements and limits

You must associate a core- or socket-based license configuration with the AMI.
You can't use SQL Server, SUSE, or RHEL AMIs provided by Amazon EC2 with Dedicated Hosts.
You can't target a specific host by choosing a host ID, and you can't enable instance affinity when launching an instance into a host resource group.

You can launch an instance into a host resource group using the following methods.

New console

To launch an instance into a host resource group

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Instances, Launch Instances.
Select an AMI.
Select the type of instance to launch and choose Next: Configure Instance Details.
On the Configure Instance Details page, configure the instance settings to suit your needs, and then do the following:
1. For Tenancy, choose Dedicated Host.
2. For Host resource group, choose Launch instance into a host resource group.
3. For Host resource group name, choose the host resource group in which to launch the instance.
Choose Review and Launch.
On the Review Instance Launch page, choose Launch.
When prompted, select an existing key pair or create a new one, and then choose Launch Instances.

Old console

To launch an instance into a host resource group

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Instances, Launch Instance.
Select an AMI.
Select the type of instance to launch and choose Next: Configure Instance Details.
On the Configure Instance Details page, configure the instance settings to suit your needs, and then do the following:
1. For Tenancy, choose Dedicated Host.
2. For Host resource group, choose Launch instance into a host resource group.
3. For Host resource group name, choose the host resource group in which to launch the instance.
Choose Review and Launch.
On the Review Instance Launch page, choose Launch.
When prompted, select an existing key pair or create a new one, and then choose Launch Instances.

Amazon CLI

To launch an instance into a host resource group

Use the run-instances Amazon CLI command, and in the Placement request parameter, omit the Tenancy option and specify the host resource group ARN.

PowerShell

To launch an instance into a host resource group

Use the New-EC2Instance Amazon Tools for Windows PowerShell command, and in the Placement request parameter, omit the Tenancy option and specify the host resource group ARN.

Understand auto-placement and affinity

Placement control for Dedicated Hosts happens on both the instance level and host level.

Auto-placement

Auto-placement is configured at the host level. It allows you to manage whether instances that you launch are launched onto a specific host, or onto any available host that has matching configurations.

When the auto-placement of a Dedicated Host is disabled, it only accepts Host tenancy instance launches that specify its unique host ID. This is the default setting for new Dedicated Hosts.

When the auto-placement of a Dedicated Host is enabled, it accepts any untargeted instance launches that match its instance type configuration.

When launching an instance, you need to configure its tenancy. Launching an instance onto a Dedicated Host without providing a specific HostId enables it to launch on any Dedicated Host that has auto-placement enabled and that matches its instance type.

Host affinity

Host affinity is configured at the instance level. It establishes a launch relationship between an instance and a Dedicated Host.

When affinity is set to Host, an instance launched onto a specific host always restarts on the same host if stopped. This applies to both targeted and untargeted launches.

When affinity is set to Off, and you stop and restart the instance, it can be restarted on any available host. However, it tries to launch back onto the last Dedicated Host on which it ran (on a best-effort basis).

Modify Dedicated Host auto-placement

You can modify the auto-placement settings of a Dedicated Host after you have allocated it to your Amazon account, using one of the following methods.

Modify the supported instance types

Support for multiple instance types on the same Dedicated Host is available for the following instance families: c5, m5, r5, c5n, r5n, and m5n. Other instance families support only a single instance type on the same Dedicated Host.

You can allocate a Dedicated Host using the following methods.

You can modify a Dedicated Host to change the instance types that it supports. If it currently supports a single instance type, you can modify it to support multiple instance types within that instance family. Similarly, if it currently supports multiple instance types, you can modify it to support a specific instance type only.

To modify a Dedicated Host to support multiple instance types, you must first stop all running instances on the host. The modification takes approximately 10 minutes to complete. The Dedicated Host transitions to the pending state while the modification is in progress. You can't start stopped instances or launch new instances on the Dedicated Host while it is in the pending state.

To modify a Dedicated Host that supports multiple instance types to support only a single instance type, the host must either have no running instances, or the running instances must be of the instance type that you want the host to support. For example, to modify a host that supports multiple instance types in the m5 instance family to support only m5.large instances, the Dedicated Host must either have no running instances, or it must have only m5.large instances running on it.

You can modify the supported instance types using one of the following methods.

New console

To modify the supported instance types for a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the Navigation pane, choose Dedicated Host.
Select the Dedicated Host to modify and choose Actions, Modify host.
Do one of the following, depending on the current configuration of the Dedicated Host:
- If the Dedicated Host currently supports a specific instance type, Support multiple instance types is not enabled, and Instance type lists the supported instance type. To modify the host to support multiple types in the current instance family, for Support multiple instance types, choose Enable.
  
  You must first stop all instances running on the host before modifying it to support multiple instance types.
- If the Dedicated Host currently supports multiple instance types in an instance family, Enabled is selected for Support multiple instance types. To modify the host to support a specific instance type, for Support multiple instance types, clear Enable, and then for Instance type, select the specific instance type to support.
  
  You can't change the instance family supported by the Dedicated Host.
Choose Save.

Old console

To modify the supported instance types for a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the Navigation pane, choose Dedicated Host.
Select the Dedicated Host to modify and choose Actions, Modify Supported Instance Types.
Do one of the following, depending on the current configuration of the Dedicated Host:
- If the Dedicated Host currently supports a specific instance type, No is selected for Support multiple instance types. To modify the host to support multiple types in the current instance family, for Support multiple instance types, select Yes.
  
  You must first stop all instances running on the host before modifying it to support multiple instance types.
- If the Dedicated Host currently supports multiple instance types in an instance family, Yes is selected for Support multiple instance types, and Instance family displays the supported instance family. To modify the host to support a specific instance type, for Support multiple instance types, select No, and then for Instance type, select the specific instance type to support.
  
  You can't change the instance family supported by the Dedicated Host.
Choose Save.

Amazon CLI

To modify the supported instance types for a Dedicated Host

Use the modify-hosts Amazon CLI command.

The following command modifies a Dedicated Host to support multiple instance types within the m5 instance family.


aws ec2 modify-hosts --instance-family m5 --host-ids h-012a3456b7890cdef

The following command modifies a Dedicated Host to support m5.xlarge instances only.


aws ec2 modify-hosts --instance-type m5.xlarge --instance-family --host-ids h-012a3456b7890cdef

PowerShell

To modify the supported instance types for a Dedicated Host

Use the Edit-EC2Host Amazon Tools for Windows PowerShell command.

The following command modifies a Dedicated Host to support multiple instance types within the m5 instance family.


PS C:\> Edit-EC2Host --InstanceFamily m5 --HostId h-012a3456b7890cdef

The following command modifies a Dedicated Host to support m5.xlarge instances only.


PS C:\> Edit-EC2Host --InstanceType m5.xlarge --HostId h-012a3456b7890cdef

Modify instance tenancy and affinity

You can change the tenancy of an instance from dedicated to host, or from host to dedicated, after you have launched it. You can also modify the affinity between the instance and the host. To modify either instance tenancy or affinity, the instance must be in the stopped state.

Note

For T3 instances, you can't change the tenancy from dedicated to host, or from host to dedicated. Attempting to make one of these unsupported tenancy changes results in the InvalidTenancy error code.

You can modify an instance's tenancy and affinity using the following methods.

Console

To modify instance tenancy or affinity

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
Choose Instances, and select the instance to modify.
Choose Instance state, Stop.
Open the context (right-click) menu on the instance and choose Instance Settings, Modify Instance Placement.
On the Modify Instance Placement page, configure the following:
- Tenancy—Choose one of the following:
  - Run a dedicated hardware instance—Launches the instance as a Dedicated Instance. For more information, see Dedicated Instances.
  - Launch the instance on a Dedicated Host—Launches the instance onto a Dedicated Host with configurable affinity.
- Affinity—Choose one of the following:
  - This instance can run on any one of my hosts—The instance launches onto any available Dedicated Host in your account that supports its instance type.
  - This instance can only run on the selected host—The instance is only able to run on the Dedicated Host selected for Target Host.
- Target Host—Select the Dedicated Host that the instance must run on. If no target host is listed, you might not have available, compatible Dedicated Hosts in your account.
For more information, see Understand auto-placement and affinity.
Choose Save.

Amazon CLI

To modify instance tenancy or affinity

Use the modify-instance-placement Amazon CLI command. The following example changes the specified instance's affinity from default to host, and specifies the Dedicated Host that the instance has affinity with.


aws ec2 modify-instance-placement --instance-id i-1234567890abcdef0 --affinity host --host-id h-012a3456b7890cdef

PowerShell

To modify instance tenancy or affinity

Use the Edit-EC2InstancePlacement Amazon Tools for Windows PowerShell command. The following example changes the specified instance's affinity from default to host, and specifies the Dedicated Host that the instance has affinity with.


PS C:\> Edit-EC2InstancePlacement -InstanceId i-1234567890abcdef0 -Affinity host -HostId h-012a3456b7890cdef

View Dedicated Hosts

You can view details about a Dedicated Host and the individual instances on it using the following methods.

New console

To view the details of a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Dedicated Hosts.
On the Dedicated Hosts page, select a host.
For information about the host, choose Details.

Available vCPUs indicates the vCPUs that are available on the Dedicated Host for new instance launches. For example, a Dedicated Host that supports multiple instance types within the c5 instance family, and that has no instances running on it, has 72 available vCPUs. This means that you can launch different combinations of instance types onto the Dedicated Host to consume the 72 available vCPUs.

For information about instances running on the host, choose Running instances.

Old console

To view the details of a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Dedicated Hosts.
On the Dedicated Hosts page, select a host.
For information about the host, choose Description. Available vCPUs indicates the vCPUs that are available on the Dedicated Host for new instance launches. For example, a Dedicated Host that supports multiple instance types within the c5 instance family, and that has no instances running on it, has 72 available vCPUs. This means that you can launch different combinations of instance types onto the Dedicated Host to consume the 72 available vCPUs.

For information about instances running on the host, choose Instances.

Amazon CLI

To view the capacity of a Dedicated Host

Use the describe-hosts Amazon CLI command.

The following example uses the describe-hosts (Amazon CLI) command to view the available instance capacity for a Dedicated Host that supports multiple instance types within the c5 instance family. The Dedicated Host already has two c5.4xlarge instances and four c5.2xlarge instances running on it.


$  aws ec2 describe-hosts --host-id h-012a3456b7890cdef


"AvailableInstanceCapacity": [
    { "AvailableCapacity": 2,
      "InstanceType": "c5.xlarge",
      "TotalCapacity": 18 },
    { "AvailableCapacity": 4,
      "InstanceType": "c5.large",
      "TotalCapacity": 36 }
  ],
"AvailableVCpus": 8

PowerShell

To view the instance capacity of a Dedicated Host

Use the Get-EC2Host Amazon Tools for Windows PowerShell command.


PS C:\> Get-EC2Host -HostId h-012a3456b7890cdef

Tag Dedicated Hosts

You can assign custom tags to your existing Dedicated Hosts to categorize them in different ways, for example, by purpose, owner, or environment. This helps you to quickly find a specific Dedicated Host based on the custom tags that you assigned. Dedicated Host tags can also be used for cost allocation tracking.

You can also apply tags to Dedicated Hosts at the time of creation. For more information, see Allocate Dedicated Hosts.

You can tag a Dedicated Host using the following methods.

New console

To tag a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Dedicated Hosts.
Select the Dedicated Host to tag, and then choose Actions, Manage tags.
In the Manage tags screen, choose Add tag, and then specify the key and value for the tag.
(Optional) Choose Add tag to add additional tags to the Dedicated Host.
Choose Save changes.

Old console

To tag a Dedicated Host

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
In the navigation pane, choose Dedicated Hosts.
Select the Dedicated Host to tag, and then choose Tags.
Choose Add/Edit Tags.
In the Add/Edit Tags dialog box, choose Create Tag, and then specify the key and value for the tag.
(Optional) Choose Create Tag to add additional tags to the Dedicated Host.
Choose Save.

Amazon CLI

To tag a Dedicated Host

Use the create-tags Amazon CLI command.

The following command tags the specified Dedicated Host with Owner=TeamA.


aws ec2 create-tags --resources h-abc12345678909876 --tags Key=Owner,Value=TeamA

PowerShell

To tag a Dedicated Host

Use the New-EC2Tag Amazon Tools for Windows PowerShell command.

The New-EC2Tag command needs a Tag object, which specifies the key and value pair to be used for the Dedicated Host tag. The following commands create a Tag object named $tag, with a key and value pair of Owner and TeamA respectively.


PS C:\> $tag = New-Object Amazon.EC2.Model.Tag
PS C:\> $tag.Key = "Owner"
PS C:\> $tag.Value = "TeamA"

The following command tags the specified Dedicated Host with the $tag object.


PS C:\> New-EC2Tag -Resource h-abc12345678909876 -Tag $tag

Monitor Dedicated Hosts

Amazon EC2 constantly monitors the state of your Dedicated Hosts. Updates are communicated on the Amazon EC2 console. You can view information about a Dedicated Host using the following methods.

The following table explains the possible Dedicated Host states.

State	Description
`available`	Amazon hasn't detected an issue with the Dedicated Host. No maintenance or repairs are scheduled. Instances can be launched onto this Dedicated Host.
`released`	The Dedicated Host has been released. The host ID is no longer in use. Released hosts can't be reused.
`under-assessment`	Amazon is exploring a possible issue with the Dedicated Host. If action must be taken, you are notified via the Amazon Web Services Management Console or email. Instances can't be launched onto a Dedicated Host in this state.
`pending`	The Dedicated Host cannot be used for new instance launches. It is either being modified to support multiple instance types, or a host recovery is in progress.
`permanent-failure`	An unrecoverable failure has been detected. You receive an eviction notice through your instances and by email. Your instances might continue to run. If you stop or terminate all instances on a Dedicated Host with this state, Amazon retires the host. Amazon does not restart instances in this state. Instances can't be launched onto Dedicated Hosts in this state.
`released-permanent-failure`	Amazon permanently releases Dedicated Hosts that have failed and no longer have running instances on them. The Dedicated Host ID is no longer available for use.

Release Dedicated Hosts

Any running instances on the Dedicated Host must be stopped before you can release the host. These instances can be migrated to other Dedicated Hosts in your account so that you can continue to use them. These steps apply only to On-Demand Dedicated Hosts.

You can release a Dedicated Host using the following methods.

After you release a Dedicated Host, you can't reuse the same host or host ID again, and you are no longer charged On-Demand billing rates for it. The state of the Dedicated Host is changed to released, and you are not able to launch any instances onto that host.

Note

If you have recently released Dedicated Hosts, it can take some time for them to stop counting towards your limit. During this time, you might experience LimitExceeded errors when trying to allocate new Dedicated Hosts. If this is the case, try allocating new hosts again after a few minutes.

The instances that were stopped are still available for use and are listed on the Instances page. They retain their host tenancy setting.

Purchase Dedicated Host Reservations

You can purchase reservations using the following methods:

Console

To purchase reservations

Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.
Choose Dedicated Hosts, Dedicated Host Reservations, Purchase Dedicated Host Reservation.
On the Purchase Dedicated Host Reservation screen, you can search for available offerings using the default settings, or you can specify custom values for the following:
- Host instance family—The options listed correspond with the Dedicated Hosts in your account that are not already assigned to a reservation.
- Availability Zone—The Availability Zone of the Dedicated Hosts in your account that aren't already assigned to a reservation.
- Payment option—The payment option for the offering.
- Term—The term of the reservation, which can be one or three years.
Choose Find offering and select an offering that matches your requirements.
Choose the Dedicated Hosts to associate with the reservation, and then choose Review.
Review your order and choose Order.

Amazon CLI

To purchase reservations

Use the describe-host-reservation-offerings Amazon CLI command to list the available offerings that match your needs. The following example lists the offerings that support instances in the m4 instance family and have a one-year term.

Note
The term is specified in seconds. A one-year term includes 31,536,000 seconds, and a three-year term includes 94,608,000 seconds.
```
aws ec2 describe-host-reservation-offerings --filter Name=instance-family,Values=m4 --max-duration 31536000
```
The command returns a list of offerings that match your criteria. Note the offeringId of the offering to purchase.
Use the purchase-host-reservation Amazon CLI command to purchase the offering and provide the offeringId noted in the previous step. The following example purchases the specified reservation and associates it with a specific Dedicated Host that is already allocated in the Amazon account, and it applies a tag with a key of purpose and a value of production.
```
aws ec2 purchase-host-reservation --offering-id hro-03f707bf363b6b324 --host-id-set h-013abcd2a00cbd123 --tag-specifications 'ResourceType=host-reservation,Tags={Key=purpose,Value=production}'
```

PowerShell

To purchase reservations

Use the Get-EC2HostReservationOffering Amazon Tools for Windows PowerShell command to list the available offerings that match your needs. The following examples list the offerings that support instances in the m4 instance family and have a one-year term.

Note
The term is specified in seconds. A one-year term includes 31,536,000 seconds, and a three-year term includes 94,608,000 seconds.
```
PS C:\> $filter = @{Name="instance-family"; Value="m4"}
```
```
PS C:\> Get-EC2HostReservationOffering -filter $filter -MaxDuration 31536000
```
The command returns a list of offerings that match your criteria. Note the offeringId of the offering to purchase.
Use the New-EC2HostReservation Amazon Tools for Windows PowerShell command to purchase the offering and provide the offeringId noted in the previous step. The following example purchases the specified reservation and associates it with a specific Dedicated Host that is already allocated in the Amazon account.
```
PS C:\> New-EC2HostReservation -OfferingId hro-03f707bf363b6b324 -HostIdSet h-013abcd2a00cbd123
```

View Dedicated Host reservations

You can view information about the Dedicated Hosts that are associated with your reservation, including:

The term of the reservation
The payment option
The start and end dates

You can view details of your Dedicated Host reservations using the following methods.

Tag Dedicated Host Reservations

You can assign custom tags to your Dedicated Host Reservations to categorize them in different ways, for example, by purpose, owner, or environment. This helps you to quickly find a specific Dedicated Host Reservation based on the custom tags that you assigned.

You can tag a Dedicated Host Reservation using the command line tools only.

Javascript is disabled or is unavailable in your browser.

To use the Amazon Web Services Documentation, Javascript must be enabled. Please refer to your browser's Help pages for instructions.

Dedicated Hosts

Host recovery