Default configuration of the host system storage

The default host profile requires three storage devices in the following strict order:

  1. Boot device and operating system storage

    This device contains boot data and operating system data. It is partitioned using the GUID Partition Table (GPT) labels. The root file system is an ext4 file system created on top of an LVM logical volume. For a detailed layout, refer to the table below.

  2. Local volumes device

    This device contains an ext4 file system with directories mounted as persistent volumes to Kubernetes. These volumes are used by the Mirantis Container Cloud services to store its data, including monitoring and identity databases.

  3. Ceph storage device

    This device is used as a Ceph datastore or Ceph OSD on managed clusters. It is used as a Ceph datastore or Ceph OSD.

Warning

Any data stored on any device defined in the fileSystems list can be deleted or corrupted during cluster (re)deployment. It happens because each device from the fileSystems list is a part of the rootfs directory tree that is overwritten during (re)deployment.

Examples of affected devices include:

  • A raw device partition with a file system on it

  • A device partition in a volume group with a logical volume that has a file system on it

  • An mdadm RAID device with a file system on it

  • An LVM RAID device with a file system on it

The wipe field (deprecated) or wipeDevice structure (recommended since Container Cloud 2.26.0) have no effect in this case and cannot protect data on these devices.

Therefore, to prevent data loss, move the necessary data from these file systems to another server beforehand, if required.

The following table summarizes the default configuration of the host system storage set up by the Container Cloud bare metal management.

Default configuration of the bare metal host storage

Device/partition

Name/Mount point

Recommended size, GB

Description

/dev/sda1

bios_grub

4 MiB

The mandatory GRUB boot partition required for non-UEFI systems.

/dev/sda2

UEFI -> /boot/efi

0.2 GiB

The boot partition required for the UEFI boot mode.

/dev/sda3

config-2

64 MiB

The mandatory partition for the cloud-init configuration. Used during the first host boot for initial configuration.

/dev/sda4

lvm_root_part

100% of the remaining free space in the LVM volume group

The main LVM physical volume that is used to create the root file system.

/dev/sdb

lvm_lvp_part -> /mnt/local-volumes

100% of the remaining free space in the LVM volume group

The LVM physical volume that is used to create the file system for LocalVolumeProvisioner.

/dev/sdc

-

100% of the remaining free space in the LVM volume group

Clean raw disk that is used for the Ceph storage back end on managed clusters.

If required, you can customize the default host storage configuration. For details, see Create a custom host profile.