Configure storage

MAAS lets you choose different storage layouts when deploying machines. These layouts affect performance, flexibility, and compatibility (e.g. UEFI vs. non-UEFI). Picking the right one ensures deployments succeed and fit your workload.

Cheat sheet

Layout

Best for

Key notes

Flat

Simple setups, small servers

One root partition, minimal options

LVM

Flexibility & growth

Resize or add volumes later

Bcache

Performance boost

Needs SSD for caching, defaults to writethrough

VMFS6

VMware ESXi hosts

Creates OS + VMFS datastore automatically

Blank

Custom/manual setups

Wipes disks, must configure storage manually

You can configure layouts when:

  • Commissioning a new machine.

  • Editing a machine’s storage before deployment.

In the UI: choose Machines > [machine] > Storage.

In the CLI: use maas $PROFILE machine set-storage-layout.

Flat layout

What it is: A simple setup where the entire disk is one root filesystem. Good for small or simple systems.

| Name | Size | Type | Filesystem | Mount point | | sda | - | disk | - | - | | sda1 | 512 MB | part | FAT32 | /boot/efi | | sda2 | rest of sda| part | ext4 | / |

How to configure:

  • UI: Choose Flat in the storage layout dropdown.

  • CLI:

    maas $PROFILE machine set-storage-layout $SYSTEM_ID layout=flat

Options:

  • boot_size: Size of /boot. Default is 0 (combined with /).

  • root_device: Device to hold the root partition (default: boot disk).

  • root_size: Size of root partition (default: 100%).

LVM layout

What it is: Logical Volume Manager (LVM) adds flexibility, allowing resizing or adding volumes later.

| Name | Size | Type | Filesystem | Mount point | | sda | - | disk | - | - | | sda1 | 512 MB | part | FAT32 | /boot/efi | | sda2 | rest of sda | part | lvm-pv(vgroot) | - | | lvroot| rest of sda | lvm | ext4 | / |

How to configure:

  • UI: Select LVM in storage layout.

  • CLI:

    maas $PROFILE machine set-storage-layout $SYSTEM_ID layout=lvm

Options:

  • vg_name: Name of the volume group (default: vgroot).

  • lv_name: Name of logical volume (default: lvroot).

  • lv_size: Size of LV (default: 100%).

Bcache layout

What it is: Uses an SSD as a cache for a slower backing disk to improve performance.

| Name | Size | Type | Filesystem | Mount point | | sda | - | disk | - | - | | sda1 | 512 MB | part | FAT32 | /boot/efi | | sda2 | rest of sda | part | bc-backing | - | | sdb(ssd)| - | disk | - | - | | sdb1 | 100% of sdb | part | bc-cache | - | | bcache0| per sda2 | disk | ext4 | / |

How to configure:

  • UI: Select Bcache in storage layout.

  • CLI:

    maas $PROFILE machine set-storage-layout $SYSTEM_ID layout=bcache

Options:

  • cache_device: SSD to use as cache (default: smallest SSD).

  • cache_mode: Cache mode (writethrough by default).

  • cache_size: Partition size for cache.

  • cache_no_part: Whether to skip partition creation on cache device.

If no SSD is present, bcache layout will fail.

VMFS6 layout

What it is: Required for VMware ESXi deployments. Sets up both the OS and VMFS datastore.

| Name | Size | Type | Use | | sda | - | disk | - | | sda1 | 3 MB | part | EFI | | sda2 | 4 GB | part | Basic Data | | sda3 | Remaining | part | VMFS Datastore 1 |

How to configure:

  • UI: Select VMFS6 when editing storage.

  • CLI:

    maas $PROFILE machine set-storage-layout $SYSTEM_ID layout=vmfs6

Options:

  • root_size: Size of datastore (default: remainder of disk).

Blank layout

What it is: Wipes the disk and leaves storage unconfigured. Use this if you want to manually define partitions, filesystems, or RAIDs before deployment.

How to configure:

  • UI: Select Blank in storage layout.

  • CLI:

    maas $PROFILE machine set-storage-layout $SYSTEM_ID layout=blank

A machine with Blank layout cannot deploy until storage is manually configured.

Safety nets

  • Always confirm layout with maas $PROFILE machine read $SYSTEM_ID | jq .storage.

  • In UI, check the Storage tab before hitting Deploy.

  • Test deployment of a machine before applying custom layouts widely.

Next steps