Compute resources are a critical part of the cloud. Compute resources have types which they inherit from the zone to which they belong. You can select the type of CloudBoot compute resource during the creation process. Also, this section provides information on how to edit CloudBoot compute resources for different types of servers and how to delete them. 

CloudBoot compute resources are created via the AdminSettings menu. To add a compute resource:

Configure the IP range which the Control Panel will assign to compute resources.

Add specific compute resources to the Control Panel itself.

After you create a compute resource you need to add it to a compute zone of the required type. For more information on compute zone types, refer to Zone Types.

Configure IP Range

To configure an IP range:

  1. Go to your Control Panel > Admin > Settings menu and click the Compute resources icon.
  2. Click the CloudBoot IPs tab – this is where you add IP addresses to the compute resource management interfaces, which compute resources will acquire via DHCP when they boot. It is recommended to locate compute resources management interfaces on a separate subnet with a NIC on the CP server also attached. In this configuration, the management subnet can use private address space and does not need to be externally addressable.

  3. Create a CloudBoot IP net.
  4. Add an IP range to the IP net.
  5. Add a CloudBoot IP address.
  6. Next, power on your compute resources. As they boot, the Control Panel will detect and record their MAC addresses. 

The dynamic range should be quite a bit larger than the actual IPs that will get assigned. This allows space for reassigning new nodes that come online, without creating address collisions.

Compute resource management interfaces must be on the same subnet as the Control Panel server, and addresses must be valid for that addressable subnet. The compute resource management interface must also have PXE boot enabled.

Create CloudBoot Compute Resource

To create a CloudBoot compute resource:

  1. Go to your Control Panel > Admin > Settings > Compute Resources menu.
  2. Click the Add New CloudBoot Compute Resource button at the bottom of the screen.
  3. Fill in the wizard step by step. Each of these steps is described in the corresponding sections below.
  4. Click the Create CloudBoot Compute Resource button to start the creation process.

Step 1 of 5. Type

At this step, select the type of CloudBoot compute resource you want to create:

Please note that starting from OnApp 6.5 we do not support Xen.

  • KVM - KVM CloudBoot Compute Resource based on CentOS 6

  • KVM - KVM CloudBoot Compute Resource based on CentOS 7
  • Xen 4 - Xen 4 CloudBoot Compute Resource based on CentOS 6

  • Xen 4 - Xen 4 CloudBoot Compute Resource based on CentOS 7
  • Backup - CloudBoot Provisioning and Backup Resource for backups maintenance, based on CentOS 6

  • Backup -  CloudBoot Provisioning and Backup Resource for backups maintenance, based on CentOS 7
  • Smart - KVM Cloudboot Compute Resource with hardware pass-through based on CentOS 6

  • Smart - KVM Cloudboot Compute Resource with hardware pass-through based on CentOS 7

  • Baremetal - XEN CloudBoot Compute Resource, where you can deploy a baremetal server based on CentOS 6 (legacy provisioning)

  • Baremetal - KVM CloudBoot Compute Resource, where you can deploy a baremetal server based on CentOS 7 (new provisioning)

Click Next to proceed to the following step of the wizard to specify the MAC Address.

Step 2 of 5. MAC Address

At this step, select MAC IP Address of the new compute resource. It will be picked up automatically when you first PXE boot a new server on your cluster using the Control Panel. 

Should you receive the "No available Compute Resources discovered" message, you can wait (this step is auto-refreshed every 30 seconds) or click the Refresh button until MAC IP Address appears.

Click Next to proceed to the following step of the wizard to specify the properties.

Step 3 of 5. Properties

At this step, specify the CloudBoot compute resource properties:

  • Label - give the compute resource a name
  • Pxe IP address - select an IP address for this compute resource from the address pool available
  • Enabled - move the slider to the right to allow VSs to be installed/booted on this compute resource
  • Compute Zone - select the compute zone, to which this compute resource will be assigned, from the drop-down list

  • Apply Compute Zone Custom Config - move this slider to the right to apply a compute zone custom config

    If this check box is selected, a compute zone custom config is applied before a compute resource custom config.

  • Custom Config - specify any custom commands you want to run when the compute resource is booted

    Centos now defaults to NFSv4. This is known to cause compatibility issues so we strongly recommend that you use NFSv3 for all mounts. This can be done by passing  -t nfs -o vers=3 in any mount commands.

    We strongly recommend that you recheck if custom config doesn't break any functionality. So before putting in production, the server with changed custom config should be rebooted, and the server behaviour rechecked. We recommend to perform the Storage Health Check and Network Health Check.

  • Show Advanced settings - move this slider to the right to specify advanced compute resource settings:
    • Backup IP address - add a provisioning network IP address
    • CPU Units - set the number of CPU units which will be assigned to the compute resource
    • Collect Stats - move the slider to the right to collect statistics for this compute resource. If you create a Backup CloudBoot resource type, the Collect Stats parameter is not available
    • Disable Failover - move the slider to the right to disable VS migration to another compute resource if this compute resource is marked as offline by the Control Panel server

      • Failover option is not available for baremetal servers.
      • If you use automatic failover with write-back caching you may lose some data in the event of a failover.
    • MTU - specify the maximum transportation unit size. You can set the frame size from 1500 to 9000 bytes

      The maximum transportation unit (MTU) is the maximum size of a unit that can be transmitted transferred via ethernet traffic. Any data that exceed the specified MTU value will be divided into smaller units before being transferred. Utilization of jumbo frames allows you to reduce/increase throughput (depending on a set frame size) and increase CPU utilization during large size file transfers. 

    • SAN bonding mode - choose bonding mode type from the drop-down menu

      After editing the SAN bonding mode option, it is required to reboot your Compute Resource to apply the settings.

      Please note, that using more than one NIC for SAN subnet requires switch support. Please ensure that your network infrastructure supports the utilized NIC bonding and is configured correctly. By default, the utilized NICs bonding mode is  IEEE 802.3ad Dynamic link aggregation which requires grouping appropriate ports together according to the section 5 Switch Configuration of Linux Ethernet Bonding Driver guide.

    • Storage Controller RAM - specify the storage controller RAM value. You may calculate the amount of memory needed for a storage controller as DB size (128 MB by default) + 10 MB x vDisk parts at the controller.
    • Storage Controller DB size - select the storage controller DB size value (minimum 128 MB, maximum 256 MB) 
    • Drives per Controller -  specify the number of disks per controller virtual server. You can specify from 1 to 4 disks. By default, the controller virtual server is created per 4 disk drives
    • Dom0 RAM - allocate the amount of memory in MB for Dom0 on Xen compute resources. You need to allocate at least 4096 MB of Dom0 RAM
    • Power Cycle Command - arbitrary command string to be executed by IPMI from the CP server. If the command is entered, a new option "Power Cycle Compute resource" - which will execute the entered command will appear at Admin > Settings > Compute Resources > label of a compute resource > Actions > Resource Options

      Currently, a command or commands should be written in one line separated with semicolon. If the command(s) is written in two lines you will receive a "fail" response, although the transaction will be performed.

Click Next to proceed to the following step of the wizard.

Step 4 of 5. Devices

At this step the compute resource is rebooted and the new configuration, set in step 3, is applied. It can take some time (the wizard makes 10 attempts with 1 minute interval). Once the compute resource comes back online you will be shown a list of devices that it contains - currently these are disks, cache settings and network interfaces. After the compute resource is created these devices can be further managed from the Control Panel (Admin > Settings > Compute Resources > label of compute resource > Actions > Resource OptionsManage devices).

Devices are unassigned by default. You can assign disks and network interfaces to a particular task.


Disks can be assigned to Storage (typical option when disk is connected to Integrated Storage) or to Cache (as cache device). To assign disks to one of these tasks, click on the required task near the device. Move the Format all assigned disks slider to the right to enable formatting for all disks, which are assigned to a particular task. You will get a confirmation pop-up window before formatting disks.

When you assign disk to Cache, then SSD caching is enabled. This feature increases disk I/O performance. There are two basic cache modes of operation:

  • Write-through: improves read I/O performance, no impact on reliability
  • Write-back: improves both read and write I/O performance, small chance of data loss.

Caching can be configured on two levels: per data store and per disk. For more information, refer to the SSD Caching section of OnApp Storage guide.

Cache Settings

Cache settings include the following options: 

  • Number of cache mirrors - specify the number of cache mirrors for the compute resource
  • Number of cache stripes - specify the number of cache stripes for the compute resource

Network Interfaces

Network interfaces can be assigned to SAN. Using more than one NIC for SAN subnet requires switch support. Ensure that your network infrastructure supports the utilized NIC bonding and is configured correctly. 

Ensure that the Compute Resource Devices permissions are on before managing devices. For more information, refer to the OnApp Permissions section of this guide.

Click Next to proceed to the following step of the wizard.

Step 5. Finalize

At this step, wait until compute resource devices configuration is applied. Then you will be indicated that compute resource is successfully configured and ready for operation. Click the Complete button. The compute resource will be added to the system. You can view it under the Compute Resources menu. You do not need to power cycle the compute resource manually, the Control Panel handles this remotely and takes care of the configuration automatically.