Exkurs: Configuring a software RAID upon interactive installation

Peter Boy, Stephen Daley, Kevin Fenzi Verze F37-F41 Last review: 2024-10-27
This Exkurs describes the configuration of a software RAID as part of an interactive Fedora Server Edition installation. In this case, the RAID capability is provided by operating system drivers and processed bei the computer CPU. It does not cover firmware raid (also called Windows RAID), which provide this capability via the computer internal firmware, nor hardware raid, where dedicated integrated hardware modules or adapters completely relieve the computer CPU of the raid processing.

The RAID configuraton starts at the "Installation Destination" window.

The Installation Destination window

001 installationdestination

The Local Standard Disk list must include at least two hard disks. And please, ignore the USB drive that provides the installation system, in case Anaconda doesn’t hide the installation media anyway.

Before you start with partitioning, you have to determine the boot type of your system, UEFI boot or BIOS (or legacy) boot system. Fedora defaults to the GPT partitioning scheme which was created with UEFI boot systems in mind. On a BIOS boot system, it requires a special partition.

Just in case you need a DOS/MBR partitioning scheme for some good reason, you can override the GPT default by adding "inst.mbr" to the kernel boot parameter at the initial boot screen.

If you don’t know the type of your system for sure, you can check the system now. Open a temporay shell by using <alt>+<ctrl>+<F2> and type into the terminal window:

# [ -d /sys/firmware/efi ] && echo UEFI || echo BIOS

The command shows in the next line either UEFI or BIOS. Use <alt>+<ctrl>+<F6> to return to the installation screen.

There are then two installation options:

  • The "Custom" option

    This way you just specify the mountpoints and Anaconda performs all the necessary steps for you. If needed you can adjust some properties afterwards. That’s the comfortable way.

    Unfortunately, Anaconda does not necessarily keep the arrangement of the partitions that you have chosen, but sorts the partitions as it sees fit. This causes no problems at all in everyday operation. But if, for example, you have placed a partition at the end to preserve the possibility of making adjustments later, that could go wrong.

  • the "Advanced Custom (Blivet-GUI)" option

    (coming soon)

Select all drives you want to include in the prospective RAID drive, click on the partitioning option you want to use and then on Done in the uper left corner.

Custom partitioning

Anaconda opens a new window:

The custom partitioning start up screen

101 custom start

  1. Check all disks for existing partitions

    If the area beyond Unknown contains one or more partition, check whether you want to retain, reuse, or delete it. Mind that you can only reuse partitions that are set up identically on all disks.

    To delete a partition, click on it and then on the '-' sign at the bottom. At the end, all disks must either be empty or identically partitioned.

  2. On a BIOS boot system, add a biosboot partition on each disk

    Use the "+" sign to add a partition. In the Mount Point field select 'biosboot' and set a size of 1 MiB.

    A biosboot entry appears in the left New Fedora 41 Installation section on one of he disks.

    Repeat it and you see a second entry, usually on the same disk.

    105 custom biosboot 1

    Select the new entry and click on Modify at Device(s). In the device list select one of the other disks. Then select Update Settings.

    Anaconda updates the list of partitions in the New Fedora 41 installation section so that the biosboot partition is now the first partition on different disks.

    110 custom biosboot 2

    Repeat the step until all disks have a biosboot partition. This is necessary so that the system can boot from any of the other disks if the first disk fails.

  3. On a UEFI boot system, add an EFI partition

    Use the "+" sign to add a partition. The "Add a new Mount Point form" form opens up

    • select /boot/efi as the mount point

    • enter 600 Mib as size

    • Tick "Add Mount Point"

    The installation window refreshes and now shows a /boot/efi partition on the left side under SYSTEM and a number of properties for this partition on the right side.

    Initial EFI system partition

    120 custom efi 1

    Anaconda sets up an EFI partition on the first disk. But a RAID system must be able to boot from any of the available disks, not just the first one. Otherwise, the system would be paralyzed if that failed. One solution is to set up the EFI partition as a RAID as well.

    Find the property Device Type and use the drop down list to change Standard partition to RAID. In the right side shows up a new selection box RAID level showing initially RAID1 (mirroring) in this example, because we have just 2 disks. Leave the file system as “EFI System Partition”. Choose an optional label, e.g. sysefi, and And trigger “Update Settings” further below.

    Final EFI system partition properties

    125 custom efi 2 # (comming soon)

  4. Add a boot Partition

    Tick the "+" sign and a form "Add a new Mount Point" opens again.

    • select /boot as the mount point

    • enter 1 Gib as size

    • Tick "Add Mount Point"

    A new mount point is created on sda1. On the right side there is a form to show and modify some properties. Find the property Device Type and use the drop down list to change Standard partition to RAID. In the right side shows up a new selection box RAID level showing initially RAID1 (mirroring) in this example, because we have just 2 disks. Choose the RAID level you wish and then click on Update Settings further down.

    Anaconda updates the form and the list beyond New Fedora 41 Installation. The sdx partition is gone and replaced by a (device) name, the same one you find in the property form on the right side. In the form you can add a label, e.g. sysboot, if you like, and Update Settings again.

    Final properties of the boot device (raid partition)

    130 custom finalbootform

  5. Add a root mount point

    Use the "+" sign to add another Moint Point

    • select / as the mount point

    • enter 15 Gib as size

    • Tick "Add Mount Point"

    Anaconda creates a new mount point. From the context Anaconda guesses to assign the device type LVM, to create a Volume Group using the default name fedora appending the systems hostname, if you already configured the network, and to assign the device name root. The size of 15 GiB is the same as a default configuration would do. That’s a lot of work that Anaconda saves you.

    Anaconda generated LVM root volume and filesystem

    140 custom generated root

    Now you have the opportunity the adjust Anacondas guessings.

    The most important one is to adjust the RAID level. Anaconda configures a LVM without RAID by default. Tick the modify button of the LVM property.

    Anaconda LVM properties form

    145 custom lvm properties

    Select a proper RAID level and check the size policy. Automatic means that the size of the partition and the Volume Group is just as large as the Logical Volumes you create with Anaconda here. That provides you a maximum of flexibilty to later adjust the storage organisation but also involves some additional steps to handle the Volume Group and its partition when you want do add a Logical Volume and file system. Alternatively you can set the Volume Group to maximum size, so you can add Logical Volumes with a minimum of effort, or a fixed size that fulfills your foreseeable requirements and leaving some space for later adjustments that come up as a surprise.

  6. Customize the storage organisation to your requirements

    Finally, you can further customize the storage organization to your requirements.

    Some adminmistrators like to confine the /var/log subdirectory in its own Logical Volume. This prevents excessive logging from filling up the root file system. But also vice versa, that excessive outputs of a program fill up the root file system to such an extent that no more log outputs can be saved and troubleshooting is made more difficult.

Finally, click on Done, in the upcomming list accept the Changes and return now to the original guide, probably Fedora Server interactive local installation guide.