Add verbose mode for detailed error messages

Added --verbose flag that enables detailed logging:
- log_error(): Always shown, critical errors
- log_warn(): Shown in verbose mode, potential issues
- log_info(): Shown in verbose mode, informational messages

Now provides helpful feedback for:
- SMART query failures with specific error messages
- Missing drive mappings for the current host
- Empty bays (no device at configured PCI path)
- Ceph command availability and query status
- Drive mapping statistics (mapped vs empty)

Color-coded output when using --color with --verbose.

Fixes: #14

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

driveAtlas.sh

@@ -28,6 +28,7 @@ OPTIONS:
     -d, --debug         Enable debug output (show drive mappings)
     -s, --skip-smart    Skip SMART data collection (faster)
     -c, --color         Enable colored output
+    --verbose           Show detailed error messages and warnings
     --no-ceph           Skip Ceph OSD information
     --show-pci          Show PCI paths in output
 
@@ -35,6 +36,7 @@ EXAMPLES:
     $(basename "$0")                  # Normal run with all features
     $(basename "$0") --skip-smart     # Fast run without SMART data
     $(basename "$0") --color          # Run with colored output
+    $(basename "$0") --verbose        # Show all errors and warnings
     $(basename "$0") --debug          # Show mapping debug info
 
 ENVIRONMENT VARIABLES:
@@ -51,6 +53,7 @@ SKIP_SMART=false
 SKIP_CEPH=false
 SHOW_PCI=false
 USE_COLOR=false
+VERBOSE=false
 
 while [[ $# -gt 0 ]]; do
     case "$1" in
@@ -82,6 +85,10 @@ while [[ $# -gt 0 ]]; do
             USE_COLOR=true
             shift
             ;;
+        --verbose)
+            VERBOSE=true
+            shift
+            ;;
         *)
             echo "Unknown option: $1" >&2
             echo "Use --help for usage information." >&2
@@ -175,6 +182,52 @@ colorize_header() {
     fi
 }
 
+#------------------------------------------------------------------------------
+# log_error
+#
+# Logs an error message to stderr. Always shown regardless of verbose mode.
+# Args: $1 - error message
+#------------------------------------------------------------------------------
+log_error() {
+    if [[ "$USE_COLOR" == true ]]; then
+        echo -e "${COLOR_RED}ERROR:${COLOR_RESET} $1" >&2
+    else
+        echo "ERROR: $1" >&2
+    fi
+}
+
+#------------------------------------------------------------------------------
+# log_warn
+#
+# Logs a warning message to stderr. Only shown in verbose mode.
+# Args: $1 - warning message
+#------------------------------------------------------------------------------
+log_warn() {
+    if [[ "$VERBOSE" == true ]]; then
+        if [[ "$USE_COLOR" == true ]]; then
+            echo -e "${COLOR_YELLOW}WARN:${COLOR_RESET} $1" >&2
+        else
+            echo "WARN: $1" >&2
+        fi
+    fi
+}
+
+#------------------------------------------------------------------------------
+# log_info
+#
+# Logs an informational message to stderr. Only shown in verbose mode.
+# Args: $1 - info message
+#------------------------------------------------------------------------------
+log_info() {
+    if [[ "$VERBOSE" == true ]]; then
+        if [[ "$USE_COLOR" == true ]]; then
+            echo -e "${COLOR_CYAN}INFO:${COLOR_RESET} $1" >&2
+        else
+            echo "INFO: $1" >&2
+        fi
+    fi
+}
+
 #------------------------------------------------------------------------------
 # Dependency Checks
 # Verifies required commands are available before running
@@ -499,7 +552,13 @@ build_drive_map() {
     declare -g -A DRIVE_MAP=()
     declare -g -A BAY_TO_PCI_PATH=()
 
-    if [[ -n "$mapping" ]]; then
+    if [[ -z "$mapping" ]]; then
+        log_warn "No drive mapping found for host '$host'. Run diagnose-drives.sh to create one."
+        return
+    fi
+
+    local mapped_count=0
+    local empty_count=0
     while read -r path slot; do
         [[ -z "$path" || -z "$slot" ]] && continue
 
@@ -507,9 +566,14 @@ build_drive_map() {
         if [[ -L "/dev/disk/by-path/$path" ]]; then
             local drive="$(readlink -f "/dev/disk/by-path/$path" | sed 's/.*\///')"
             DRIVE_MAP[$slot]="$drive"
+            ((mapped_count++))
+        else
+            log_info "Bay $slot: No device at PCI path $path"
+            ((empty_count++))
         fi
     done <<< "$mapping"
-    fi
+
+    log_info "Mapped $mapped_count drives, $empty_count empty bays"
 }
 
 #------------------------------------------------------------------------------
@@ -530,9 +594,12 @@ build_ceph_cache() {
 
     # Skip if ceph-volume is not available
     if ! command -v ceph-volume &>/dev/null; then
+        log_info "ceph-volume not found, skipping Ceph OSD detection"
         return
     fi
 
+    log_info "Querying Ceph OSD information..."
+
     # Parse ceph-volume lvm list output
     # Format: blocks starting with "====== osd.X =======" followed by device info
     local current_osd=""
@@ -549,9 +616,12 @@ build_ceph_cache() {
 
     # Skip if ceph command is not available
     if ! command -v ceph &>/dev/null; then
+        log_info "ceph CLI not found, skipping OSD status detection"
         return
     fi
 
+    log_info "Querying Ceph OSD status..."
+
     # Parse ceph osd tree for status
     # Format: ID  CLASS  WEIGHT   TYPE NAME        STATUS  REWEIGHT
     while IFS= read -r line; do
@@ -607,7 +677,22 @@ get_drive_smart_info() {
     local serial="-"
     local warnings=""
 
-    smart_info="$(sudo smartctl -A -i -H "/dev/$device" 2>/dev/null)"
+    # Capture both stdout and stderr for better error reporting
+    local smart_stderr
+    smart_stderr="$(mktemp)"
+    smart_info="$(sudo smartctl -A -i -H "/dev/$device" 2>"$smart_stderr")"
+    local smart_exit=$?
+
+    if [[ $smart_exit -ne 0 && -s "$smart_stderr" ]]; then
+        log_warn "SMART query failed for $device: $(head -1 "$smart_stderr")"
+    fi
+    rm -f "$smart_stderr"
+
+    if [[ -z "$smart_info" ]]; then
+        log_info "No SMART data available for $device"
+        echo "HDD|-|✗|-|-|"
+        return
+    fi
 
     # Temperature parsing - handles multiple formats:
     # - SATA: "194 Temperature_Celsius ... 35" (value at end of line)