Dedicated hosts
In this article:
Dedicated hosts#
General information#
Dedicated host is a physical server provisioned to you only, i.e. no one else can run instances on it. Server types differ in configuration – the number of available physical cores, sockets, and RAM. What types of instances can be run on a dedicated host depends on the CPU generation used.
Instances of different types can be hosted on the same host, as long as it has enough resources to run them. The number of instances supported depends on physical cores and memory available and on vCPU and memory requirements of each individual instance.
To use the service, send a request for a dedicated host. The gen5, gen5p, and gen6 servers can be ordered, equipped with Intel® Xeon® Gold 6254 Processor, Intel® Xeon® Gold 6244 Processor, and Intel® Xeon® Gold 6348 Processor, respectively (see server generation table in the documentation on instances). Typically, they have 256 GB to 1.5 TB RAM in case of gen5 and gen5p CPUs and 1 to 3 TB in case of gen6 CPUs.
In addition, the following options are available for dedicated hosts:
GPU installed
Nested virtualization enabled
1C optimized
Note
Up to 5% of CPU resources of a dedicated host and 5-10% of its RAM (depending on the available amount) are used to ensure cloud infrastructure operation.
Auto-placement and affinity to the host#
If you have several dedicated hosts, you can choose the host to run a particular instance on, or you can let the cloud do this for you.
By default, a given dedicated host can accommodate only those instances for which it is specified as the target one. In order for the cloud to use this host also to accommodate instances for which the target host is not specified, the Auto-placement option must be enabled on this host.
If you want the instance always to run on the same dedicated host, specify the affinity to the target host when the instance is created. Otherwise, once stopped, the instance can be started on another host, even if a specific dedicated host was initially selected for it.
Placement groups#
If you have multiple dedicated hosts, you can distribute instances across them, using placement group functionality. This minimizes the number of failed instances from the same group if one of the dedicated hosts fails.
To run an instance from the group on a specific dedicated host, the latter must have the Auto-placement option enabled. To host an instance, the server having the fewest available resources and hosting no other instances from the group is selected.
The standard limit is five instances per placement group.
Note
A group can include instances deployed both on dedicated and shared hosts, but you’d better not mix them.
Migration in case of failure#
In the event of a dedicated host failure (for example, due to network connection loss), you will be provisioned with another host having similar characteristics (if available).
The new host gets the same ID as the failed one. Accordingly, all instances that had affinity to the failed host will be launched on the replacement host. Instances having no affinity to the failed host can be launched on another host if it has more resources available.
If the instance is stopped and its host then fails, the instance will be migrated and started on another host depending on its affinity. If there is an affinity, it will be started on a new host with the same ID. Otherwise, it will be started on the host, which has the least available resources.
Managing dedicated hosts#
Ordering a dedicated host#
Dedicated host are provisioned upon request. To use the service and receive a personal offer, make the request:
Go to the Instances section Dedicated Hosts.
Click Create.
In your request, please specify:
Host type — Preferred host configuration.
Lease term — Minimum lease term is three months.
The number of hosts.
Availability zone — Preferred NGN data center where the hosts will be located.
Describe the tasks you want to use dedicated hosts for. This will help us assess what resources you will need and select the optimal tariff.
Click Submit the request.
Creating an instance on a dedicated host#
Creating an instance on a dedicated host is similar to that on a shared host, except for step 2. Therefore, below we will describe only those parameters that must be set for a dedicated host.
Select an image.
To create an instance, select an image with the OS you want to use.
Select the instance place
At this step, you need to specify where in the cloud the instance will be placed.
Placement Group — When you select a placement group, its member instances will be started on different computing nodes. To use the placement group, create it first. For more information, see the documentation on placement groups.
Placement type — To start an instance on a dedicated host, select the respective option and set additional parameters.
Dedicated Host — If you want the instance to be started on a particular host, select the dedicated host from the drop-down list. Otherwise, leave the default value (Auto-placement), in which case the instance will be started on a randomly selected dedicated host with Auto-placement enabled.
Affinity — If you select Target Host, the stopped instance will always start on the same host. If there is no affinity, it may be started on another host.
Note
For more information about auto-placement and instance affinity, see the corresponding section of the documentation.
For details on the remaining steps, see section how to create an instance using the wizard of the documentation.
Note
When a particular dedicated host is selected, we proceed to Instance Type, the next step. Here, the Available column of the type description table displays information about how many instances of a certain type can be started on the selected host. If the host is not selected (i.e. Auto-placement option is enabled), you will see the total number of instances of this type that can be started on all dedicated hosts with this option enabled.
Creating a launch template for a dedicated host#
You can create a template to launch same-type instances on a dedicated host. The procedure is similar to that of creating a template to launch an instance on a shared host.
To create a launch template, go to the respective section and click Create.
Select an image.
From the list of images, select the pre-built OS image you want to use to create the instance and click Select.
Select the instance place
At this step, you need to select where in the cloud the instance will be placed.
Placement group
Placement type — To start the instance on a dedicated host, select the Dedicated Host option and set additional parameters.
Auto-placement or particular dedicated host.
Creating instance affinity to the dedicated host.
Complete the remaining steps as described in the creating a launch template section.
Enable auto-placement on a host#
To allow instances with Auto-placement selected to run on a host, enable auto-placement on this host first:
Go to the Dedicated Hosts section.
Select the dedicated host in the resource table.
Click Enable auto-placement.
In the window that opens, confirm the action.
You can also enable auto-placement for a host in the Information tab on the host’s page by toggling the respective switch.
Disable auto-placement#
By default, auto-placement of instances on a dedicated host is disabled. To disable it for hosts where it was previously enabled:
Go to the Dedicated Hosts section.
Select the dedicated host in the resource table. You can select multiple hosts at once.
Click Disable auto-placement.
In the window that opens, confirm the action.
You can also disable auto-placement for a host in the Information tab on the host’s page by toggling the respective switch.
Delete a dedicated host#
If for some reason you no longer need a dedicated host, then submit a request to disable it. For this:
Go to the Dedicated Hosts section.
Select the host to be deleted in the resource table.
Click Delete.
In the request form that opens, describe the reason why you don’t want to use the host anymore.
Click Submit the request.
Information about a dedicated host#
General information about available dedicated hosts can be viewed in the resource table in the Dedicated Hosts section.
To view detailed information about a specific dedicated host in the Dedicated Hosts section, find the desired instance in the table and click on the link with its ID. This will open the dedicated host page.
The Information tab#
Here you can see key dedicated host features and parameters:
Name tag (editable field)
host status
supported instance families
availability zone where the dedicated host is placed
number of physical cores
number of sockets
used and total number of CCU
used and total amount of RAM
auto-placement option (toggle switch)
creation date
Resource tab#
The tab contains a table of all instance types supported by the dedicated host, along with their parameters. The Available column displays the number of instances of a particular type that can be started on the host, given the remaining resources.
Instances tab#
The table in the tab displays information about the instances running on the dedicated host: their ID, owner and type.
Tags tab#
The Tags tab displays all tags assigned to the dedicated host. You can edit existing and add new tags.