Cache lsblk output to reduce redundant calls

Instead of calling lsblk twice per device (once for size, once for
mount points), now performs a single lsblk call at start and caches:
- LSBLK_SIZE: Device sizes
- LSBLK_MOUNTS: Mount points (accumulated for partitions)

This reduces the number of subprocess calls significantly,
especially on systems with many drives.

Fixes: #16

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

driveAtlas.sh

@@ -856,6 +856,25 @@ done
 # Combine numeric bays (sorted numerically) with m2 slots (sorted alphanumerically)
 all_bays=$(printf '%s\n' "${!DRIVE_MAP[@]}" | grep -E '^[0-9]+$' | sort -n; printf '%s\n' "${!DRIVE_MAP[@]}" | grep -E '^m2-' | sort)
 
+# Cache lsblk data to reduce redundant calls
+# Single call gets all info we need: size and mount points
+declare -A LSBLK_SIZE=()
+declare -A LSBLK_MOUNTS=()
+log_info "Caching block device information..."
+while IFS='|' read -r name size mounts; do
+    [[ -z "$name" ]] && continue
+    LSBLK_SIZE[$name]="$size"
+    # Accumulate mount points for parent device
+    parent="${name%%[0-9]}"  # Strip partition number
+    if [[ -n "$mounts" ]]; then
+        if [[ -n "${LSBLK_MOUNTS[$parent]}" ]]; then
+            LSBLK_MOUNTS[$parent]+=",${mounts}"
+        else
+            LSBLK_MOUNTS[$parent]="$mounts"
+        fi
+    fi
+done < <(lsblk -rn -o NAME,SIZE,MOUNTPOINT 2>/dev/null)
+
 # Parallel SMART data collection for faster execution
 # Collect SMART data in background jobs, store in temp files
 if [[ "$SKIP_SMART" != true ]]; then
@@ -878,7 +897,8 @@ fi
 for bay in $all_bays; do
     device="${DRIVE_MAP[$bay]}"
     if [[ -n "$device" && "$device" != "EMPTY" && -b "/dev/$device" ]]; then
-        size="$(lsblk -d -n -o SIZE "/dev/$device" 2>/dev/null)"
+        # Use cached lsblk data
+        size="${LSBLK_SIZE[$device]:-}"
 
         # Get SMART info from cache (or defaults if skipped)
         if [[ "$SKIP_SMART" == true ]]; then
@@ -914,11 +934,12 @@ for bay in $all_bays; do
             fi
         fi
 
-        # Check mount points using lsblk (includes partitions)
-        # This catches both whole-device mounts and partition mounts (e.g., /dev/sda1)
+        # Check mount points using cached lsblk data
+        # This includes both whole-device mounts and partition mounts
         usage="-"
-        mount_points="$(lsblk -n -o MOUNTPOINT "/dev/$device" 2>/dev/null | grep -v '^$' | head -3 | tr '\n' ',')"
-        mount_points="${mount_points%,}"  # Remove trailing comma
+        mount_points="${LSBLK_MOUNTS[$device]:-}"
+        # Limit to first 3 mount points for display
+        mount_points="$(echo "$mount_points" | tr ',' '\n' | head -3 | tr '\n' ',' | sed 's/,$//')"
         if [[ -n "$mount_points" ]]; then
             if [[ "$mount_points" == *"/"* && ! "$mount_points" == *"/boot"* && ! "$mount_points" == *"/home"* ]]; then
                 # Root filesystem mounted (but not just /boot or /home)