Android companion in testing

Cairn

Know your backups are actually working.

Cairn is a self-hosted dashboard for the health of every backup on your ZFS hosts. It understands backups specifically: how far behind replication is, whether each dataset has three copies in two places with one off-site, and what is backed up by nothing at all.

It also watches its own alerting, because the alerter is sometimes the thing that broke. Cairn for Android pairs with your Cairn server by QR code and puts that status on your phone.

What it does

• Replication lag, pool health, scrubs and SMART in one view
• Borg, restic, rclone, snapper and backupninja support
• A 3-2-1 scorecard and a "backed up by nothing" view
• Email and Gotify alerts, with a self-test of the alert path
• Android app with a home-screen widget, notifications, and file recovery
• Runs entirely on your own hardware: no cloud, no phone-home

Runs on: Self-hosted server (Linux, Docker) + Android 14 and newer