I’ve been using restic for a while under Linux to backup to Backblaze B2 and it’s been great. My scripts already do a check after every backup. I’ve done spot checks to see if files seem to be backed up, but I haven’t tested a full restore yet. Even though I trust restic and check, it seems like it would be a good idea to test a full restore.
Does anyone have any suggestions or scripts to test a full restore? Do you just restore to a temp directory and walk the directories you back up and do a diff of some sort? I do have enough room on my drive to do a full restore to a temp directory on that drive, but is there a way to test a restore without doing that?
If you don’t use Windows you can run restic mount, then compare your source data with the mounted data. I believe this is as close you can come to restore without actually restoring to disk.
The comparison can be done directly using a suitable diff tool, or indirectly by means of comparing lists of e.g. md5sum hashes.
If you want to test a full restore, I recommend you use the same command you would use to do the actual full restore. Else you test another functionality than the one you intend to use
About alternatives for restore: The restore command is the most optimized one and especially is able to minimize traffic from the backend which all other alternatives (mount or dump) are not able to. So, to do a real restore, restore is the recommended command to use.
The way I test (small home user, not a business) is to go "I’m going to pretend my mailserver crashed and my wife urgently needs an email from 2 years ago” and to test I can restore it.
Until I can read the email on my screen, I don’t consider the test passed.
My constraint on restore test is disk space, not network/traffic.
And since restore test is much more frequent, I’d rather test with dump.
And if I think ‘restore’ will behave differently than ‘dump’, then I’ll just use dump to restore when an actual disaster happens.
bottom line: I optimise for the part that happens more often, in a way that I can background it and look at the result later, knowing that nothing is happening to my disk space during this operation.
I was curious what gemini had to say about this, so I had it create this bash script for me. What do you think? I’ll of course go through it in detail to make sure I understand everything before running it, but after a quick glance it seemed reasonable.
#!/bin/bash
# --- Configuration ---
REPO_PATH="/path/to/your/repository"
RESTIC_PASSWORD="your_password_here"
FILES_FROM="/path/to/your/backup_list.txt"
RESTORE_BASE="/tmp/restic_restore_test"
# Options: "diff" or "checksum"
VERIFY_MODE="checksum"
# Set to true to skip downloads and just check if snapshots exist
DRY_RUN=false
export RESTIC_PASSWORD="$RESTIC_PASSWORD"
# Tracking variables for the summary
PASSED_PATHS=()
FAILED_PATHS=()
# --- Helper: Space Check ---
check_space_availability() {
local path_to_restore=$1
local target_dir=$2
# Get uncompressed size of the latest snapshot for this path
local req_size=$(restic -r "$REPO_PATH" stats latest --path "$path_to_restore" --mode raw-data --json | grep -oP '"total_size":\s*\K\d+')
# Get available space on target partition in bytes
local avail_size=$(df -B1 "$target_dir" | awk 'NR==2 {print $4}')
if [ "$req_size" -gt "$avail_size" ]; then
return 1 # Not enough space
fi
return 0
}
# --- Initialization ---
if [[ ! -f "$FILES_FROM" ]]; then
echo "Error: File list $FILES_FROM not found."
exit 1
fi
mkdir -p "$RESTORE_BASE"
echo "--- Starting Restic Restore Drill (Mode: $VERIFY_MODE) ---"
# --- Main Loop ---
while IFS= read -r SOURCE_PATH || [[ -n "$SOURCE_PATH" ]]; do
[[ -z "$SOURCE_PATH" || "$SOURCE_PATH" =~ ^# ]] && continue
echo "------------------------------------------------"
echo "Processing: $SOURCE_PATH"
# 1. Handle Dry Run
if [ "$DRY_RUN" = true ]; then
if restic -r "$REPO_PATH" ls latest --path "$SOURCE_PATH" > /dev/null 2>&1; then
PASSED_PATHS+=("$SOURCE_PATH (Dry Run - Found)")
else
FAILED_PATHS+=("$SOURCE_PATH (Dry Run - Not Found)")
fi
continue
fi
# 2. Check Space Availability
if ! check_space_availability "$SOURCE_PATH" "$RESTORE_BASE"; then
echo "❌ Skip: Insufficient space for $SOURCE_PATH"
FAILED_PATHS+=("$SOURCE_PATH (Out of Space)")
continue
fi
# 3. Perform Restore
CURRENT_TARGET="${RESTORE_BASE}_$(echo "$SOURCE_PATH" | tr '/' '_')"
mkdir -p "$CURRENT_TARGET"
echo "Restoring data..."
if restic -r "$REPO_PATH" restore latest --target "$CURRENT_TARGET" --path "$SOURCE_PATH" > /dev/null 2>&1; then
RESTORED_DATA_PATH="${CURRENT_TARGET}${SOURCE_PATH}"
echo "Verifying integrity..."
# 4. Verification Mode Logic
if [ "$VERIFY_MODE" == "diff" ]; then
diff -rq "$SOURCE_PATH" "$RESTORED_DATA_PATH" > /dev/null
RESULT=$?
else
# Checksum Mode
find "$SOURCE_PATH" -type f -exec sha256sum {} + | sort > /tmp/src.hash
find "$RESTORED_DATA_PATH" -type f -exec sha256sum {} + | sed "s|$RESTORED_DATA_PATH|$SOURCE_PATH|g" | sort > /tmp/res.hash
diff /tmp/src.hash /tmp/res.hash > /dev/null
RESULT=$?
rm -f /tmp/src.hash /tmp/res.hash
fi
if [ $RESULT -eq 0 ]; then
echo "✅ Success!"
PASSED_PATHS+=("$SOURCE_PATH")
else
echo "❌ Integrity Mismatch!"
FAILED_PATHS+=("$SOURCE_PATH (Data Mismatch)")
fi
else
echo "❌ Restore Failed!"
FAILED_PATHS+=("$SOURCE_PATH (Restic Error)")
fi
# Cleanup individual path to free space for the next one
rm -rf "$CURRENT_TARGET"
done < "$FILES_FROM"
# --- Final Summary Report ---
echo -e "\n========================================"
echo " RESTIC TEST SUMMARY"
echo "========================================"
echo "Date: $(date)"
echo "Mode: $VERIFY_MODE | Dry Run: $DRY_RUN"
echo "----------------------------------------"
if [ ${#PASSED_PATHS[@]} -ne 0 ]; then
echo "✅ PASSED:"
for p in "${PASSED_PATHS[@]}"; do echo " - $p"; done
fi
if [ ${#FAILED_PATHS[@]} -ne 0 ]; then
echo -e "\n❌ FAILED:"
for f in "${FAILED_PATHS[@]}"; do echo " - $f"; done
exit 1
else
echo -e "\n✨ All paths verified successfully!"
exit 0
fi
In my opinion, the script is useless because you just wrote a system test for restic. You probably want to go 1 level up to the acceptance testing, or even DR, as the current test duplicates what is already tested in restic codebase.
