[Yandex Cloud documentation](../../index.md) > [Yandex BareMetal](../index.md) > [Concepts](index.md) > Setup and management > Additional server settings

# Advanced server settings

{% note warning %}

BareMetal servers use optimal [BIOS](https://en.wikipedia.org/wiki/BIOS) settings by default. We do not recommend changing them.

{% endnote %}

To implement some use cases for your server, you may need to modify its default basic settings. For example, to [install](../operations/servers/reinstall-os-from-own-image.md) a [Windows Server](https://en.wikipedia.org/wiki/Windows_Server) OS onto a partition created in a fault-tolerant [RAID](disks/raid.md) array, you can [create](#creating-rst-raids) a RAID array with the integrated controller of your server’s motherboard (if your server’s motherboard has an integrated RAID controller).

At the hardware level, BareMetal servers are managed by a baseboard management controller (BMC) via the [IPMI](https://en.wikipedia.org/wiki/Intelligent_Platform_Management_Interface).

Modifying BMC settings by the user will lead to the following:
* Server management via the [KVM console](../operations/servers/server-kvm.md) will be unavailable.
* You will be unable to stop, start, or restart the server using the [management console](https://console.yandex.cloud), Yandex Cloud [CLI](../../cli/cli-ref/baremetal/cli-ref/index.md), or [API](../../api-design-guide/index.md).
* You will be unable to reinstall the server OS.
* You will be unable to view server hardware health metrics (processor temperature, fan speed, etc.)

{% note alert %}

If the user modifies BMC settings, Yandex BareMetal cannot guarantee the correct operation of the KVM console and other server management tools.

{% endnote %}

## Server disk space management {#storage-management}

When you lease a server with an OS [installed](../operations/servers/reinstall-os-from-marketplace.md) from a Marketplace image, one or more [software RAID arrays](disks/raid.md#software-raid) of the [RAID 1](https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_1) and/or [RAID 10](https://en.wikipedia.org/wiki/Nested_RAID_levels#RAID_10) levels are created on the server’s [disks](disks/disk-types.md) depending on its default configuration. The number of arrays created by default depends on how many different disk types your server uses.

In the lease form for a server with a pre-installed OS, click **Configure disk layout** to reconfigure its default RAID arrays, repartition the disk space into software RAID arrays, or opt out of their use.

{% note alert %}

The use of RAID arrays ensures fault tolerance and may prevent data loss if one or more disks fail, depending on your RAID level. The exception is [RAID 0](https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_0), which provides no fault tolerance.

{% endnote %}

### Managing disk space when installing an OS from a custom image {#manual-storage-management}

When you lease a server without an OS, the server's disks are not arranged into RAID arrays.

You can manually manage the server’s disk space when installing an OS from a custom image:
* Create [software RAID arrays](disks/raid.md#software-raid) during OS installation if this technology is supported at the OS [kernel](https://en.wikipedia.org/wiki/Kernel_(operating_system)) level (e.g., in [Linux](https://en.wikipedia.org/wiki/Linux) systems).

    Some operating systems and software products do not allow you to create software RAID arrays during installation (e.g., [Microsoft Windows](https://en.wikipedia.org/wiki/Microsoft_Windows) or VMware [ESXi](https://en.wikipedia.org/wiki/VMware_ESXi)).

    The exact supported levels of software RAID arrays may vary depending on your OS.
* Before OS installation, [create](#creating-rst-raids) logical RAID arrays [using an integrated RAID controller](disks/raid.md#fake-raid) if your server's motherboard has integrated RAID or `Fake RAID`controllers, such as [Intel RST](https://en.wikipedia.org/wiki/Intel_Rapid_Storage_Technology) or `AMD RAIDXpert`. For your OS to use such RAID arrays, you may need to pre-install a driver for the integrated RAID controller.

    Some operating systems and software products do not support RAIDs created on Fake RAID controllers (e.g., VMware [ESXi](https://en.wikipedia.org/wiki/VMware_ESXi)).

* Opt out of using RAID arrays and create [partitions](https://en.wikipedia.org/wiki/Disk_partitioning) directly on [HDDs](https://en.wikipedia.org/wiki/Hard_disk_drive), [SSDs](https://en.wikipedia.org/wiki/Solid-state_drive), or [NVMe](https://en.wikipedia.org/wiki/NVM_Express) disks.

    This option does not provide disk fault tolerance: if a disk fails, any data stored on that disk will be lost.

### Features of RAID arrays created with integrated RAID controllers {#rst-raids}

Depending on the specific model, a BareMetal server's motherboard may have one or two integrated RAID controllers or none at all.

Here are the possible types of Intel RST integrated RAID controllers on server motherboards:
* SATA (Serial AT Attachment): Supports only the [SATA](https://en.wikipedia.org/wiki/SATA) interface.
* SCU (Storage Controller Unit): Supports the SATA and [SAS](https://en.wikipedia.org/wiki/Serial_Attached_SCSI) interfaces.

Integrated RAID controllers are implemented at the motherboard firmware level, emulating a block device with the basic bootloader functionality; full operation at the OS level requires installing a dedicated driver.

{% note warning %}

When installing Linux in legacy mode onto a RAID array created using an integrated RAID controller, you may be unable to select a boot disk for starting the OS. To resolve this issue, exclude one physical disk from any RAID arrays or [install](#install-os-uefi) the OS in UEFI mode.

{% endnote %}

#### Supported RAID levels {#supported-raid-levels}

You can use integrated Intel RST RAID controllers to create RAID arrays at the following levels:

* [RAID 0](https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_0): Striping. Such an array may consist of two to six disks. This RAID type improves the read and write speed but reduces fault tolerance: if any single disk in the array fails, your data will be lost.
* [RAID 1](https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_1): Mirroring. Such an array may consist of two disks. This RAID type does not improve the speed of reading or writing data but provides fault tolerance: you will not lose data if one of the disks fails.
* [RAID 5](https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_5): Striping with distributed parity. Such an array may consist of three to six disks. This RAID type improves the read speed and ensures fault tolerance: you will not lose data if one of the disks fails.

    {% note info %}

    In some motherboard models, the SCU RAID controller does not support creating RAID 5 arrays.

    {% endnote %}

* [RAID 10](https://en.wikipedia.org/wiki/Nested_RAID_levels#RAID_10): `RAID 1` striping. Such an array may consist of 4 to 12 disks, and their total number must always be even. This RAID type improves both the read and write speed while providing fault tolerance: data will be lost only if both disks in a `RAID 1` within the `RAID 10` fail.

#### Limitations when creating RAID arrays {#raid-array-limitations}

When using integrated Intel RST RAID controllers to create RAID arrays, the following limitations apply:

* You can create a maximum of two RAID arrays on a single disk group.
* You can only set the size for the _first_ RAID array you create on a disk group.

    The _second_ RAID array created on the same disk group will use all the unallocated disk space left after the first RAID array was created.
* The _second_ RAID array you create using a certain disk must comprise exactly the same disks as the first array. 

    For example, if your first `RAID 0` array contains three disks, `A`, `B`, and `C`, the second array you can create from these disks may be either another `RAID 0` array or a `RAID 5` array since only these two levels support three-disk configurations. You will not be able to create the second array made up of two disks (e.g., `A` and `B`), other three disks (e.g., `C`, `D`, and `F`), or four disks (e.g., `A`, `B`, `C`, and `D`), because the second array must use exactly the same three disks as the first one: `A`, `B`, and `C`. However, you can create one more array on disks `E` and `F`.

### Creating RAID arrays with an integrated RAID controller, as exemplified by Intel RST {#creating-rst-raids}

{% note info %}

Depending on your server’s motherboard model, the procedure for configuring the BIOS/UEFI settings may vary.

{% endnote %}

The process for creating RAID arrays with integrated RAID controllers depends on your server's boot [mode](#boot-mode). To create a RAID array:

1. Enable RAID mode on the disk controllers:

    1. In the [KVM console](../operations/servers/server-kvm.md), access the BIOS/UEFI system settings menu by pressing **F11** or **Del** during server startup when the [POST](https://en.wikipedia.org/wiki/Power-on_self-test) screen appears. You will see the following message: `Entering Setup...`.
    1. Wait for the system settings menu to open, then use the **←** and **→** keys to navigate to the **Advanced** section.

        1. Select **SATA Configuration** and press **Enter**.
        1. In the section that opens, select **SATA Mode**, press **Enter**, and select **RAID Mode**.
        1. Press **Esc** to return to the previous menu section.
        1. Select **SCU Configuration** and press **Enter**.
        1. In the section that opens, select **SCU RAID Option ROM/UEFI Driver**, press **Enter**, and select **Enabled**.
        1. Press **Esc** to return to the previous menu section.
    1. Use the **←** and **→** keys to navigate to **Save & Exit**, select **Save Changes and Reset**, and press **Enter**.
    1. Confirm by pressing **Yes** to restart the server.
1. Configure RAID arrays:

    {% list tabs %}

    - Legacy mode

      1. Launch the RAID configuration utility by pressing **Ctrl** + **I** during server startup when you see the list of connected physical disks on the [POST](https://en.wikipedia.org/wiki/Power-on_self-test) screen.

          If the disks are connected to both the SATA and SCU server RAID controllers, the tables listing the disk will be displayed twice: the first table will have the `SATA Option ROM` header, and the second one, `SCU Option ROM`. You must access and configure each controller's settings separately.
      1. To create a RAID array, select **1. Create RAID Volume** and press **Enter**. In the window that opens:

          1. Configure the new RAID array.

              Use the **Tab** key to switch between menu items, **↑** and **↓** to view available options, and **Enter** to select a value.
          1. Select **Create Volume** and press **Enter**.
          1. Type `Y` to confirm.
      1. To delete a RAID array, select **2. Delete RAID Volume** and press **Enter**. In the window that opens:

          1. Select the RAID array you want to delete and press **Del**.
          1. Type `Y` to confirm.
          1. Press **Esc** to return to the previous menu section.
      1. To exit the RAID configuration utility, select **4. Exit** and press **Enter**.
      1. Type `Y` to confirm.

    - UEFI mode

      1. During the restart, press **F11** or **Del** again to enter the system settings menu and wait for it to open.
      1. Use the **←** and **→** keys to navigate to the **Advanced** section.
      1. To create RAID arrays from disks connected to the SCU RAID controller, select **Intel RSTe SCU Controller** and press **Enter**.

          1. To create a RAID:
          
              1. Select the **Create RAID Volume** section to configure settings and select disks for the new RAID.
              1. Click **Create Volume** to run the operation.
          1. To delete a RAID:
          
              1. In the RAID list, select the RAID in question and click **Enter**.
              1. In the window that opens, click **Delete** and confirm the deletion.
          1. Press **Esc** to return to the previous menu section.

      1. To create RAID arrays from disks connected to the SATA RAID controller, select **Intel RSTe SATA Controller** and press **Enter**.

          1. To create a RAID:
          
              1. Select the **Create RAID Volume** section to configure settings and select disks for the new RAID.
              1. Click **Create Volume** to run the operation.
          1. To delete a RAID:
          
              1. In the RAID list, select the RAID in question and click **Enter**.
              1. In the window that opens, click **Delete** and confirm the deletion.
          1. Press **Esc** to return to the previous menu section.

      1. Use the **←** and **→** keys to navigate to **Save & Exit**, select **Save Changes and Reset**, and press **Enter**.
      1. Confirm by pressing **Yes** to restart the server.

    {% endlist %}

## OS boot mode {#boot-mode}

{% note info %}

Depending on your server’s motherboard model, the procedure for configuring the BIOS/UEFI settings may vary.

{% endnote %}

BareMetal server motherboards support the _Legacy_ and _UEFI_ OS boot modes. The server's OS boot mode is configured in its motherboard's [BIOS](https://en.wikipedia.org/wiki/BIOS)/[UEFI](https://en.wikipedia.org/wiki/UEFI) system settings.

When you [install](../operations/servers/reinstall-os-from-marketplace.md) a server OS from a Marketplace image, it is always installed and booted in Legacy mode.

### Installing an OS in UEFI mode {#install-os-uefi}

You can [install](../operations/servers/reinstall-os-from-own-image.md) an OS in UEFI mode from a custom image. During installation, boot the server from the CD drive with the mounted OS installation image in UEFI mode. To do this, in the [KVM console](../operations/servers/server-kvm.md):

1. Select **Media** → **Virtual Media Wizard...** or click the CD icon in the top menu of the KVM console. In the window that opens:

    1. In the **CD/DVD Media1** section, click **Browse** and select the [previously uploaded](../operations/image-upload.md) ISO OS image in the `user-iso` directory.
    1. Click **Connect CD/DVD**.
    1. Check the **Virtual CD 1** device **Status** section to make sure the **Connected To** field now shows your selected ISO path, then click **Close**.
1. Click **Reboot to CD-ROM** in the top-right corner of the KVM console.
1. Access the BIOS/UEFI system settings menu by pressing **F11** or **Del** during server startup when the [POST](https://en.wikipedia.org/wiki/Power-on_self-test) screen appears. You will see the following message: `Entering Setup...`.
1. Wait for the system settings menu to open.
1. If you intend to install your OS onto RAID arrays [created](#creating-rst-raids) with an integrated RAID controller, use the **←** and **→** keys to navigate to the **Advanced** section.

    1. Select **PCIe/PCI/PnP Configuration** and press **Enter**.
    1. In the section that opens, select **Launch Storage OpROM policy**, press **Enter**, and select **UEFI only**.
    1. Press **Esc** to return to the previous menu section.
1. Use the **←** and **→** keys to navigate to the **Save & Exit** section.
1. If you changed any settings in the previous steps, save them: select **Save Changes**, press **Enter**, and confirm the action in the window that opens.
1. In the **Boot Override** section, select `UEFI: AMI Virtual CDROM0 1.00` and press **Enter**.

    If your **Boot Override** lacks that item, go to the **Boot** settings section and add it under **UEFI Boot Drive BBS Priorities**.

The server will restart and boot from the virtual CD drive in `UEFI` mode. In this mode, the OS installed from the image mounted on the CD drive will also be set up using `UEFI`.

### Booting an OS in UEFI mode {#start-os-uefi}

To successfully boot an OS installed in UEFI mode on your server, select the correct boot device in the BIOS/UEFI settings. To do this, in the [KVM console](../operations/servers/server-kvm.md):

1. When restarting your server after the OS installation is complete, navigate to the BIOS/UEFI system settings menu again. To do this, during server startup, press **F11** or **Del** on the [POST](https://en.wikipedia.org/wiki/Power-on_self-test) screen and wait for the system settings menu to open.
1. If the OS is installed onto RAID arrays [created](#creating-rst-raids) with an integrated RAID controller, use the **←** and **→** keys to navigate to the **Advanced** section.

    1. Select **PCIe/PCI/PnP Configuration** and press **Enter**.
    1. In the section that opens, check that the **Launch Storage OpROM policy** option is set to **UEFI only**.

        {% note info %}

        If **Launch Storage OpROM policy** is set to a different value, change it to **UEFI only**. Save the changes, restart the server, and open the BIOS/UEFI settings menu again to proceed with boot device selection.

        {% endnote %}

    1. Press **Esc** to return to the previous menu section.
1. Use the **←** and **→** keys to navigate to the **Boot** section.

    1. Select **UEFI Boot Drive BBS Priorities** and press **Enter**. In the section that opens, do the following:

        1. In the **1st Device** field, press **Enter** select an option based on the installed OS, e.g., `UEFI OS`, `Ubuntu`, `Windows Boot Manager`, etc.
        1. Press **Esc** to return to the previous menu section.
    1. In the **Set Boot Priority** section, set **1st Boot Device** to the same value you selected in **UEFI Boot Drive BBS Priorities**.
1. Use the **←** and **→** keys to navigate to **Save & Exit**, select **Save Changes and Reset**, and press **Enter**. Press **Yes** to confirm.

After completing these steps, your server OS will boot from the selected boot device in UEFI mode.