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+# 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