How to configure storage layouts
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 (writethroughby 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
- Peruse the storage reference catalog