Files
vanlink/failover/sync-usb-backup.sh
T
Andreas WredeandClaude Sonnet 5 94e6a2d811 failover: tolerate rsync's benign vanished-file exit code in backup syncs
Both sync-sd-backup.sh and sync-usb-backup.sh used set -e, so rsync
returning exit 24 (partial transfer due to vanished source files --
expected on a live root, e.g. a container's shm socket disappearing
mid-sync) aborted the script before it printed its own success message,
even though the actual file transfer completed fully. Only exit 24 is
now tolerated; any other rsync failure still aborts as before.

Found running sync-sd-backup.sh today: it transferred all 919k files
correctly but exited non-zero and skipped its completion line.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YJfEELeh3ercpRBp8yYrYS
2026-08-23 15:55:38 -04:00

62 lines
2.1 KiB
Bash
Executable File

#!/usr/bin/env bash
# Refresh the USB disk (sda) as a live boot-fallback clone of the
# running root filesystem. Run manually after a push:
# sudo ./failover/sync-usb-backup.sh
#
# EEPROM BOOT_ORDER falls back to the SD card, then this USB disk, if the
# primary boot disk (NVMe) doesn't come up. /etc/fstab, /etc/machine-id,
# and /var/log are excluded from the sync so the clone keeps its own
# partition identity (PARTUUIDs differ per disk) and boot/journal history
# instead of inheriting the source disk's — see failover/README or repo
# memory "sd-fallback-fstab-clobber" for what breaks if those leak across.
set -euo pipefail
[ "$(id -u)" -eq 0 ] || { echo "Run as root (sudo)." >&2; exit 1; }
USB_ROOT_PART=/dev/sda2
MOUNT_POINT=/mnt/usb-backup-root
root_src=$(findmnt -no SOURCE /)
if [ "$root_src" = "$USB_ROOT_PART" ]; then
echo "Currently booted from $USB_ROOT_PART — refusing to sync USB onto itself." >&2
exit 1
fi
mkdir -p "$MOUNT_POINT"
mounted_here=0
if ! mountpoint -q "$MOUNT_POINT"; then
mount "$USB_ROOT_PART" "$MOUNT_POINT"
mounted_here=1
else
mount -o remount,rw "$MOUNT_POINT"
fi
cleanup() {
if [ "$mounted_here" -eq 1 ]; then
umount "$MOUNT_POINT"
fi
}
trap cleanup EXIT
# rsync exit 24 ("partial transfer due to vanished source files") is expected on a
# live root — files like container shm sockets or in-progress logs routinely disappear
# mid-sync. Tolerate that one code; anything else is a real failure and still aborts.
rc=0
rsync -aHAX --numeric-ids --delete \
--info=progress2 \
--exclude=/proc/* --exclude=/sys/* --exclude=/dev/* --exclude=/run/* \
--exclude=/tmp/* --exclude=/mnt/* --exclude=/media/* --exclude=/lost+found \
--exclude=/boot/firmware/* --exclude=/swapfile \
--exclude=/etc/fstab --exclude=/etc/machine-id --exclude=/var/log/* \
--stats / "$MOUNT_POINT/" || rc=$?
if [ "$rc" -ne 0 ] && [ "$rc" -ne 24 ]; then
echo "rsync failed (exit $rc)." >&2
exit "$rc"
fi
if [ "$rc" -eq 24 ]; then
echo "Note: some files vanished mid-sync (rsync exit 24) — normal on a live root." >&2
fi
echo "USB backup ($USB_ROOT_PART) synced from $root_src."