Complete unified pool visualization with filesystem children

- Implement filesystem children display under physical drive pools
- Agent generates individual filesystem metrics for each mount point
- Dashboard parses filesystem metrics and displays as tree children
- Add filesystem usage, total, and available space metrics
- Support target format: drive info + filesystem children hierarchy
- Fix compilation warnings by properly using available_bytes calculation

agent/src/collectors/disk.rs

@@ -343,6 +343,9 @@ impl DiskCollector {
             storage_pools.push(pool);
         }
 
+        // IMPORTANT: Do not create individual filesystem pools when using auto-discovery
+        // All single disk filesystems should be grouped into physical drive pools above
+
         // Process mergerfs pools (these remain as logical pools)
         for pool_info in &topology.mergerfs_pools {
             if let Ok((total_bytes, used_bytes)) = self.get_filesystem_info(&pool_info.mount_point) {
@@ -887,6 +890,11 @@ impl DiskCollector {
         }
     }
 
+    /// Convert bytes to gigabytes
+    fn bytes_to_gb(&self, bytes: u64) -> f32 {
+        bytes as f32 / (1024.0 * 1024.0 * 1024.0)
+    }
+
     /// Detect device backing a mount point using lsblk (static version for startup)
     fn detect_device_for_mount_point_static(mount_point: &str) -> Result<Vec<String>> {
         let output = Command::new("lsblk")
@@ -1212,6 +1220,79 @@ impl Collector for DiskCollector {
                     });
                 }
             }
+
+            // Individual filesystem metrics for PhysicalDrive pools
+            if let StoragePoolType::PhysicalDrive { filesystems } = &storage_pool.pool_type {
+                for filesystem_mount in filesystems {
+                    if let Ok((total_bytes, used_bytes)) = self.get_filesystem_info(filesystem_mount) {
+                        let available_bytes = total_bytes - used_bytes;
+                        let usage_percent = if total_bytes > 0 {
+                            (used_bytes as f64 / total_bytes as f64) * 100.0
+                        } else { 0.0 };
+
+                        let filesystem_name = if filesystem_mount == "/" {
+                            "root".to_string()
+                        } else {
+                            filesystem_mount.trim_start_matches('/').replace('/', "_")
+                        };
+
+                        // Calculate filesystem status based on usage
+                        let fs_status = if usage_percent >= self.config.usage_critical_percent as f64 {
+                            Status::Critical
+                        } else if usage_percent >= self.config.usage_warning_percent as f64 {
+                            Status::Warning
+                        } else {
+                            Status::Ok
+                        };
+
+                        // Filesystem usage metrics
+                        metrics.push(Metric {
+                            name: format!("disk_{}_fs_{}_usage_percent", pool_name, filesystem_name),
+                            value: MetricValue::Float(usage_percent as f32),
+                            unit: Some("%".to_string()),
+                            description: Some(format!("{}: {:.0}%", filesystem_mount, usage_percent)),
+                            status: fs_status.clone(),
+                            timestamp,
+                        });
+
+                        metrics.push(Metric {
+                            name: format!("disk_{}_fs_{}_used_gb", pool_name, filesystem_name),
+                            value: MetricValue::Float(self.bytes_to_gb(used_bytes)),
+                            unit: Some("GB".to_string()),
+                            description: Some(format!("{}: {}GB used", filesystem_mount, self.bytes_to_human_readable(used_bytes))),
+                            status: Status::Ok,
+                            timestamp,
+                        });
+
+                        metrics.push(Metric {
+                            name: format!("disk_{}_fs_{}_total_gb", pool_name, filesystem_name),
+                            value: MetricValue::Float(self.bytes_to_gb(total_bytes)),
+                            unit: Some("GB".to_string()),
+                            description: Some(format!("{}: {}GB total", filesystem_mount, self.bytes_to_human_readable(total_bytes))),
+                            status: Status::Ok,
+                            timestamp,
+                        });
+
+                        metrics.push(Metric {
+                            name: format!("disk_{}_fs_{}_available_gb", pool_name, filesystem_name),
+                            value: MetricValue::Float(self.bytes_to_gb(available_bytes)),
+                            unit: Some("GB".to_string()),
+                            description: Some(format!("{}: {}GB available", filesystem_mount, self.bytes_to_human_readable(available_bytes))),
+                            status: Status::Ok,
+                            timestamp,
+                        });
+
+                        metrics.push(Metric {
+                            name: format!("disk_{}_fs_{}_mount_point", pool_name, filesystem_name),
+                            value: MetricValue::String(filesystem_mount.clone()),
+                            unit: None,
+                            description: Some(format!("Mount: {}", filesystem_mount)),
+                            status: Status::Ok,
+                            timestamp,
+                        });
+                    }
+                }
+            }
         }
 
         // Add storage pool count metric
@@ -1234,5 +1315,4 @@ impl Collector for DiskCollector {
 
         Ok(metrics)
     }
-
 }