# ZeroDownTime Alpine 

## Disklayout

Inspired by ChromeOS.

Partition | Label | Size | Comment
----------|-------|------|--------
1 | EFI | 128M | EFI Grub, Syslinux for legacy BIOS
2 | RootA | 4GB | Slot A - RootFS incl. kernel and initrd
3 | RootB | 4GB | Slot B - RootFS incl. kernel and initrd
4 | Data | 100% | (LUKS optional) + LVM: /var, ...

OS upgrades are atomic. If running using Slot A, the upgrade will install the new OS and Kernel into Slot B and switch the default boot order in grub.cfg residing in the EFI partition.

## First boot
Instance meta-data on bare-metal is stored next to EFI bootloader in partition one as yaml.

During first boot of Slot A or B, tiny-cloud will use the NoCloud meta-data yaml to bootstrap the instance.


# Resources
- https://chromium.googlesource.com/chromiumos/docs/+/HEAD/disk_format.md#x86-EFI-BIOS