Amazon EC2 Dedicated Hosts FAQs

You can start using Dedicated Hosts simply by allocating a host using EC2 Console, API, CLI, and then launching instances into them. Dedicated Hosts typically go through the following stages in their life-cycle:

1. Host Allocation: A host becomes accessible after you have allocated it in your AWS account. In order to allocate a host, you can use the AllocateHosts API or allocate-hosts - AWS CLI or use the AWS Management Console.
2. Instance placement: To launch instances on any host, you need to specify tenancy of "host" using the RunInstances API or in the AWS Management Console. To launch instances on a specific host, you need to specify the host ID as a target in the AWS Management Console or in the RunInstances API.
3. Host Release: If you no longer need to use a host, at first you need to stop or terminate all of the instances running on the host, and then you can release the host using the ReleaseHosts API or the AWS Management Console.

Alternatively, you can automate the host allocation, instance placement, and host release tasks by specifying your Dedicated Host management preferences in AWS License Manager. License Manager helps you to automate license tracking when you bring your own software licenses (viz. Windows and SQL Server licenses) to AWS. It also helps you add your existing Dedicated Hosts to the automated experience.

You can use AWS License Manager to automate the management of the licenses that you bring to EC2 Dedicated Hosts. In order to bring your own licenses (BYOL) to EC2 Dedicated Hosts and automate host management, you need to perform the following steps.

• Step 1: Define licensing rules for software licenses, such as Windows Server and SQL Server, that you want bring to AWS. We recommend that you consult with your own licensing advisors to carefully understand the terms.
• Step 2: Specify your preferences for managing the underlying hosts. For example, you can define how to allocate and release hosts, which licensing rules to use, what instance types are allowed, and whether to turn on host recovery.
• Step 3: (optional) If you want other AWS accounts in your organization to use the available capacity on the hosts, you can share the host management preferences and licensing rules across your organizational accounts.

Once configured, a user in your organization can simply launch BYOL instances just like they would launch instances with AWS-provided licenses, while AWS takes care of common administrative tasks. Most cloud providers offer limited automation for Dedicated Hosts, so administrators have to perform ongoing management tasks such as host allocation, host capacity utilization, and instance placement. In AWS, you can automate the entire management of EC2 Dedicated Hosts using AWS License Manager, and leverage EC2 capabilities such as auto-scaling with Dedicated Hosts.

Yes, once you define preferences for managing your Dedicated Hosts in AWS License Manager, you can onboard your existing Dedicated Hosts to the automated management experience with a few simple clicks and let AWS manage them on your behalf.

No, there are no additional charges for using AWS License Manager to manage Dedicated Hosts. You only pay for the Dedicated Hosts that License Manager allocates on your behalf in your AWS account. See Dedicated Hosts pricing for more information.

You can allocate Dedicated Hosts based on the limit that is associated with your account. For more information, visit documentation on AWS Service Limits. If you are using automated management, then you can set up license level limits in AWS License Manager.

Below are the capabilities available in Dedicated Hosts:

1. Multiple instance size support - You can run different instance sizes within the same instance family on a Dedicated Host by leveraging the Nitro-based instances that support this capability. This helps maximize utilization of your Dedicated Host fleet as well as your software licenses. Support for multiple instance types on the same Dedicated Host is available for the instance families listed here.
2. Instance placement control - You have the option to launch instances onto a specific Dedicated Host, which helps you meet your compliance requirements.
3. Affinity - You have the option to keep instances attached to a host even if you stop and start it, by specifying instance affinity to a particular host.
4. Continuous monitoring - You can continuously monitor and record when your instances are getting launched, stopped, or terminated on Dedicated Hosts using AWS Config recording. Continuous monitoring helps you meet your compliance requirements, such as auditing of instances launched into Dedicated Hosts.
5. Visibility of sockets and physical cores - You have visibility of the number of sockets and physical cores, which helps you meet licensing obligations of bringing physical core and socket based licenses.
6. Integrated license management - You have the option to automate the tracking and management of your software licenses on Dedicated Hosts using AWS License Manager. You can refer to AWS License Manager Documentation for more detail.
7. Automated management and auto-scaling - You can automate management of Dedicated Hosts using AWS License Manager, and you can also achieve elasticity on Dedicated Hosts by using Auto-Scaling groups.
8. Cross-account sharing - You can share resources between Dedicated Host accounts within your organization or an organizational unit by enabling cross-account sharing.
9. Host recovery - You can make instances on Dedicated Hosts more resilient by turning on Host recovery. Host recovery automatically restarts your instances on a new host in the event of an unexpected hardware failure.
10. Host Maintenance - With automated host maintenance, you can reduce your application’s downtime and offload the undifferentiated heavy-lift of host maintenance of your dedicated hosts. In the rare case of a host degradation or for planned EC2 maintenance, AWS automatically allocates a new dedicated host, and reboots your instance on the new host during a scheduled maintenance event.

The maximum number of instances you can run per host varies based on the instance type configuration you select. You can see the maximum number of instances per host on the Dedicated Host Pricing Page or in the EC2 Dedicated Host console or the DescribeHosts API.

You have the option to launch instances onto a specific Dedicated Host, or you can let Amazon EC2 place the instances automatically. Controlling instance placement allows you to deploy applications to help address licensing, corporate compliance, and regulatory requirements.

No, you do not need to place instances manually. You can use AWS License Manager to automate and let AWS manage instance placement on your behalf.

You launch instances using AWS License Manager just like you launch instances with Amazon provided licenses. You simply specify the AMI and instance type. Providing tenancy type as “host” is optional while launching instances using AWS License Manager.

Yes, in order to launch an instance while using AWS License Manager, you need to attach a host resource group to your license configuration in AWS License Manager and set up license rules so that new instances are launched as per your capacity requirements.

A host resource group is a group of Dedicated Hosts that you can manage as a single entity. You can use host resource groups to separate hosts by purpose (for example, dev/test versus production), organizational unit, or license constraint.

There are certain scenarios that require the license to remain assigned to the same physical server for a specific period of time. For example Microsoft requires that Windows Server licenses remain assigned to the same physical server for at least 90 days. By using AWS License Manager, you can set License Affinity rules to restrict a license usage for the specified number of days.

Yes, you can identify each Dedicated Host using the host-ID. In case an underlying physical server is replaced, the Dedicated Host will be given a new host-ID.

Yes, a host-ID is similar to an asset-ID of a physical server.

No, AWS will not reuse the same host-ID for different physical servers. Every physical server has a different host-ID. If AWS substitutes your underlying physical server for warranty purposes or for other AWS requirements, you will also get a new host-ID. AWS will not swap physical servers without changing the host-ID.

You can use EC2 describe-hosts API to track the number of sockets and physical cores on a Dedicated Host. You can also use AWS License Manager to automate the tracking of sockets and physical cores.

You can use Auto Scaling groups (ASG) to launch dedicated hosts into any of your Amazon Virtual Private Clouds (Amazon VPCs). To use ASG, you should create a host resource group in in AWS License Manager. Once you specify your requirements in the host resource group, you can create a launch template and then create an ASG using the launch template.

Yes, you can share Dedicated Hosts with all your AWS accounts. You have the flexibility of sharing hosts with a few accounts or with all accounts in your AWS Organizations to save costs.

Dedicated Hosts that are shared count towards the owner account’s Dedicated Hosts limits only. The limits of a member account’s Dedicated Hosts are not affected by Dedicated Hosts that have been shared with them. Similarly, instances that members launch onto shared Dedicated Hosts do not count towards their instance limits.

You can turn on host recovery through the AWS Console, or using a CLI or API. You can enable, disable and view configuration for host recovery configuration for a Dedicated Host at any time. You can also turn on host recovery for a group of Dedicated Hosts using host resource group in AWS License Manager.

The instances that run on hosts can only be assigned to Amazon Virtual Public Cloud. You cannot run an instance on a host with the EC2 Classic networking type.

No, both dedicated instances and instances running on hosts can be assigned to a dedicated Amazon VPC.

Your dedicated host may require maintenance for several reasons. Amazon may have detected degradation of the underlying hardware due to which it may need to undergo maintenance. Also, it may be triggered by routine EC2 maintenance activities. EC2 routinely performs maintenance on the underlying systems in order to strengthen the security, reliability, and operational performance of the EC2 service for our customers. Additional information about maintenance events can be found in the EC2 User Guide here. To avoid a single point of failure within critical applications, refer to our architecture center for more information on implementing fault-tolerant architectures.

The automated host maintenance feature is supported for dedicated hosts in all classic AWS regions. Automated host maintenance is currently not support in AWS Outposts, AWS Local zones and Wavelength zones.

With automated host maintenance you can reduce your application’s downtime and offload the undifferentiated operational heavy-lift of maintenance of your dedicated host. The automated scheduling and execution of the maintenance event reduces the need for any manual intervention, freeing you up to handle more important tasks, while also giving you the flexibility of controlling when your dedicated hosts are maintained. 

Host reachability:

• Host Recovery - Unreachable
• Host Maintenance - Reachable
   

Host State:

• Host Recovery - under-assessment
• Host Maintenance - permanent-failure
   

Action:

• Host Recovery - Recovery is immediate
• Host Maintenance - Maintenance is scheduled
   

Scheduling flexibility:

• Host Recovery - Cannot be rescheduled
• Host Maintenance - Cannot be rescheduled
   

Host Resource Group Support:

• Host Recovery - Supported
• Host Maintenance - Not supported

During the maintenance, your instances will be rebooted on to a new dedicated host. After the maintenance, which may take a few minutes to complete, your instance(s) will retain the same attributes as the original instances, including instance ID, private IP addresses, elastic IP addresses, EBS volume attachments, and all instance metadata. Any instance(s) that cannot be automatically rebooted on to the new host will be stopped if they are using an EBS root volume or terminated if they are using an instance store root volume 28 days after you are notified about the scheduled maintenance.

Your affected dedicated host will automatically be released after all your instances have been either rebooted on to a new replacement host or stopped. You might be able to access existing instances on the affected host before the scheduled maintenance event. However, you cannot launch new instances on this host. You will be allocated a new dedicated host prior to your scheduled maintenance activity. The replacement dedicated host will have a new host ID, but retain the same attributes as the original dedicated host, including availability zone, instance type, tags, auto placement settings, host affinity, host recovery, and host maintenance settings. If your affected dedicated host has a host reservation associated with it, then EC2 will automatically transfer the reservation to the new host.

A degraded host is considered to have permanent hardware failure and is retired. Your supported licenses including Microsoft Windows server licenses can be reassigned to another server in such a case sooner than 90 days from initial assignment. If you are using AWS License Manager to track your licenses, AWS License Manager allocates new licenses for the replacement Dedicated Host based on your license configuration limits. Once the degraded host is released, the licenses associated with it become available for reassignment.

After detecting a degradation on your dedicated host, AWS schedules the automated host maintenance event for the dedicated host for 14 days later to give you time to prepare. The duration of the host maintenance depends on multiple parameters including the type and number of instances running on the dedicated host. Usually, the maintenance event takes a few minutes to complete.

Yes, you can reschedule the host maintenance event. The event is initially scheduled for 14 days after you are notified. You have the option to reschedule the event to reboot your instances for an earlier date or for up to 7 days beyond the initial 14-day period.  To reschedule your host maintenance event, please follow the steps in the Event Scheduling Guide.

When AWS detects degradation for your dedicated host and schedules your maintenance event, you will receive an email notification providing details of the degraded host and the scheduled maintenance event. The email will also describe the maintenance time slots for the instances running on the host. In the rare scenario that host maintenance is not successful, you will receive an email notification requesting you to evict the host within 28 days of the unsuccessful maintenance event.

If you disable host maintenance, in case your dedicated host goes into a degraded or ‘permanent-failure’ state, you will receive an email notification to evict the host and manually migrate your instances to another dedicated host within 28 days. If you have a dedicated host reservation, then you will be allocated a replacement host. After 28 days the degraded host will be evicted and released automatically.

Host maintenance is automatically enabled when you are allocating a new dedicated hosts that support host maintenance through the EC2 Console. You may disable it by deselecting the “Host Maintenance” checkbox. You can also enable the feature by modifying an existing host and toggling the “Host Maintenance” feature on. EC2 API supports toggling host maintenance on and off using the API as well. For more details, please refer to the Dedicated host maintenance user guide.

No, you will not be billed for the degraded host. You will only be billed for the new host. If you had a dedicated host reservation associated with the degraded host, the reservation will be transferred to the new host. 

You are not required to specify a maintenance window. AWS manages the patching of Dedicated Hosts and other EC2 tenancy options automatically. However, if you prefer, you can specify a maintenance window to ensure AWS performs maintenance on your host only during that time window.

The following licensing options are available on Dedicated Hosts:

1. Bring your own licenses (BYOL) : You can bring your eligible existing per-socket, per-core, or per-VM software licenses, that are bound to VMs, sockets, or physical cores, as well as other types of licenses, subject to your license terms. 
2. License included (LI) : You can use Windows Server AMIs provided by AWS.
3. Amazon Linux : You can use free open source Amazon Linux OS and run any of your workloads on AWS Dedicated Hosts. Dedicated Hosts also supports License Included instances for all Linux OS (including AL, AL2, Ubuntu) except SUSE and RHEL.
4. AWS Marketplace AMIs: You can launch all AWS Marketplace AMIs on Dedicated Hosts.

You can use BYOL, Amazon Linux, Windows Server AMIs provided by Amazon, and AWS Marketplace AMIs on Dedicated Hosts.

AWS provides three different purchasing options to suit your needs and maximize your savings.

1. On-Demand: This is a non-commitment based pricing option where you pay for each second (minimum of 60 seconds) that the Dedicated Host is active in your account (or allocated). You can terminate billing for any particular On-Demand Dedicated Host by releasing it and you have the flexibility to scale up or down depending on your requirements.
2. Reserved Instances: This is a commitment based pricing option and you can purchase a Reserved Instance for a one-year or three-year commitment, with the three-year commitment offering a bigger discount. There are three payment options: All Upfront, Partial Upfront and No Upfront Reserved Instance. Reserved Instances can provide you with cost savings of up to 70% on your on-demand costs over the term.
3. Savings Plans: This is flexible pricing model that offers significant savings over On-Demand in exchange for a commitment to use a specific amount of compute power (measured in $/hour) for a one or three year period. Savings Plans automatically reduce your bills on compute usage across any AWS Region, even as usage changes. This provides you with the flexibility to use any compute option that suits your needs and helps you save up to 72% on your AWS Compute usage.

*Note: Only virtual dedicated host instances are eligible for Savings Plans at this time, .metal instances are ineligible.

For a host that is running On-Demand, you pay for each second (minimum of 60 seconds) that the host is active (or allocated) in your account, regardless of the number of instances, or types of AMIs, that are running on the host. You can terminate billing for any particular On-Demand Dedicated Host by releasing it. On-Demand instance pricing gives you the flexibility to scale up or down without long-term commitments.

Note: License Included (LI) Windows Server on Dedicated Hosts is billed on a per-hour basis.

You pay for Reserved Instances for a one-or-three year term commitment. There are three payment options: all upfront, partial upfront and no upfront.

1. All Upfront payment_: You roll the entire cost of your Dedicated Host reservation into one upfront payment. All Upfront reservation provides the best overall price compared to the partial upfront and no upfront offerings. 
2. Partial Upfront payment: You pay roughly half of the reservation cost upfront. The remaining cost is amortized (and charged hourly) across each hour in the term. The Partial Upfront payment option provides a better price than the no upfront payment option.
3. No Upfront payment: You pay nothing upfront and the entire cost of the Reserved Instance is amortized (and charged hourly) across each hour in the term.
   You can contact your account manager if you need to reserve Dedicated Hosts for a term which is greater than three years.

Reserved Instances can provide up to 70% discount compared to the On-Demand price. When you purchase a Dedicated Host reservation, you are billed for every hour during the entire term that you select, regardless of whether the instances are running or not. The effective hourly price shows the amortized hourly cost of the Dedicated Host reservation (this takes the total cost of the host reservation over the entire term, including any upfront payment, and spreads it out over each hour of the term).

For each month, the actual monthly payment will equal the actual number of hours in that month multiplied by the hourly usage rate. The hourly usage rate is equivalent to the total average monthly payments over the term divided by the total number of hours (based on a 365-day year) over the term.

No, you need to purchase and allocate Dedicated Host to your account in order to choose the Reserved Instance option.

You can purchase a Reserved Instance for Dedicated Host by allocating a certain number of hosts for a time period of one or three years. After you’ve allocated a Dedicated Host to your account, you can pay for a one or three year Reserved Instance for the Dedicated host. When you purchase a Reserved Instance and assign it to the Dedicated Host, you are committing to pay for that Dedicated Host for a minimum period of time equal to the term of the Reserved Instance.

When your Reserved Instance expires, your Dedicated Hosts will remain allocated to your account and you can continue to use the Dedicated Hosts. If you decide to not release the Dedicated Hosts, then you will be billed On-Demand after the expiration of the Reserved Instance. You will also have the option to pay for another Reserved Instance for the same Dedicated Hosts.

Subject to Microsoft licensing terms, you can bring your existing eligible Windows Server and SQL Server licenses to Dedicated Hosts. There is no additional charge for software usage if you choose to bring your own licenses.

Alternatively, you can use Windows Server Amazon Machine Images (AMIs) provided by Amazon to run the latest versions of Windows Server on Dedicated Hosts. This is common for scenarios where you have existing SQL Server licenses eligible to run on Dedicated Hosts but need Windows Server to run the SQL Server workload. To get more details about Windows Server AMIs prices refer to Dedicated host pricing page.

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