diff --git a/packages/backend/server/src/base/metrics/metrics.ts b/packages/backend/server/src/base/metrics/metrics.ts
index 29f81db142..9154a605fd 100644
--- a/packages/backend/server/src/base/metrics/metrics.ts
+++ b/packages/backend/server/src/base/metrics/metrics.ts
@@ -59,7 +59,8 @@ export type KnownMetricScopes =
   | 'mail'
   | 'ai'
   | 'event'
-  | 'queue';
+  | 'queue'
+  | 'storage';
 
 const metricCreators: MetricCreators = {
   counter(meter: Meter, name: string, opts?: MetricOptions) {
diff --git a/packages/backend/server/src/core/storage/wrappers/comment-attachment.ts b/packages/backend/server/src/core/storage/wrappers/comment-attachment.ts
index 1ef983988b..aa65d24184 100644
--- a/packages/backend/server/src/core/storage/wrappers/comment-attachment.ts
+++ b/packages/backend/server/src/core/storage/wrappers/comment-attachment.ts
@@ -4,6 +4,7 @@ import {
   autoMetadata,
   Config,
   EventBus,
+  metrics,
   OnEvent,
   type StorageProvider,
   StorageProviderFactory,
@@ -69,15 +70,23 @@ export class CommentAttachmentStorage {
       blob,
       meta
     );
+    const mime = meta.contentType ?? 'application/octet-stream';
+    const size = blob.length;
     await this.models.commentAttachment.upsert({
       workspaceId,
       docId,
       key,
       name,
-      mime: meta.contentType ?? 'application/octet-stream',
-      size: blob.length,
+      mime,
+      size,
       createdBy: userId,
     });
+
+    metrics.storage.histogram('comment_attachment_size').record(size, { mime });
+    metrics.storage.counter('comment_attachment_total').add(1, { mime });
+    this.logger.log(
+      `uploaded comment attachment ${workspaceId}/${docId}/${key} with size ${size}, mime: ${mime}, name: ${name}, user: ${userId}`
+    );
   }
 
   async get(