Skip to content
JelinaJelina DocumentationTechnical documentation
Back to website

Storage and data partition

JelinaOS storage is designed for system security and controllable data: system partitions operate read-only, and all user data resides in a separate data partition.

Storage layout

Section titled “Storage layout”
┌─────────────────────────────────────────────────────┐
│ System partition (read-only)                        │  System itself; not writable at runtime
├─────────────────────────────────────────────────────┤
│ Application area (/app, read-only + writable layers) │  Applications and components, separate from system
├─────────────────────────────────────────────────────┤
│ Data partition (/mnt/overlay/rw)                     │  All user data and writes
│   ├─ System writable layer (root upper)             │
│   ├─ Application writable layer (app upper)         │
│   ├─ Configuration files / runtime logs             │
│   └─ User files                                     │
└─────────────────────────────────────────────────────┘
  • System partitions operate read-only and cannot be modified.
  • The application area, /app, is mounted separately; application and component updates do not consume system partition space.
  • The data partition holds all user writes, isolated from applications and the system.

Where to store data

Section titled “Where to store data”
Data type Location Description
Application data Application directories in the data partition Container volumes and program runtime data
Configuration files Configuration directories in the data partition Persistent configuration retained across updates
Logs System logs + data partition Configurable retention policies
Temporary data System memory/temporary directories Cleared at reboot without using persistent storage

Check storage space

Section titled “Check storage space”
Terminal window
df -h

Pay particular attention to free space in the data partition, which provides most of the device’s usable storage.

Storage exhaustion and temporary root recovery

Section titled “Storage exhaustion and temporary root recovery”

Built-in disk space monitoring continuously protects root partition capacity. When space is nearly exhausted, the device can enter temporary root recovery mode:

  • The system boots with a temporary root using memory as the writable layer, allowing occupied space to be reclaimed without affecting data partition contents.
  • Temporary root is a recovery mode: All writes in it are lost after reboot. Use it only to access the system and free space.
  • It triggers at a storage usage threshold, 90% by default, with configurable actions: alert only, prompt for restart, or force restart.
  • Use device commands to inspect temporary root status:
Terminal window
jelina-enter-tmpfs-root --status   # View temporary-root status
jelina-info --get tmp_root --json  # Temporary-root details
  • After freeing data partition space in temporary root mode, reboot again to return to normal mode.

When space is exhausted, prioritize application logs, container images, and temporary files for cleanup. Avoid deleting system state and update markers. Do not perform business operations or configuration changes in temporary root mode.

Space management recommendations

Section titled “Space management recommendations”
  • Regular cleanup: Expired logs can consume substantial space. Limit log usage with:
    Terminal window
    journalctl --vacuum-size=200M   # Limit log storage usage
  • Monitoring and alerts: With JelinaCloud, configure storage usage alert thresholds, 80% by default, for automatic notifications.
  • Reserve capacity: Updates require temporary space. Keep more than 20% of the data partition free.

Data backups

Section titled “Data backups”

The data partition is the only persistent location for user data. Back it up regularly:

  • Back up critical data to external storage or the cloud.
  • Before major updates or maintenance, back up critical directories in the data partition.
  • Store backups outside the data partition, such as on external disks or network storage, to avoid a single point of failure.

Factory resets and data

Section titled “Factory resets and data”
  • A factory reset restores the system and user-written data to their factory state.
  • Back up important data before performing recovery.
Section titled “Related documentation”