HDDS-13284. [Docs] Add "Bucket Quota with snapshots" to "Quota in Ozone" page.

docs/05-administrator-guide/03-operations/11-quota.md

@@ -109,3 +109,26 @@ bin/ozone sh bucket info /volume1/bucket1
 ```
 
 We can get the quota value and usedNamespace in the info of volume and bucket.
+
+## Bucket Quota with snapshots
+
+Starting with Apache Ozone 2.1, bucket quota handling with snapshots is more accurate and transparent.
+When you use snapshots in Apache Ozone, deleting data (keys or directories) doesn't always mean the space or namespace count is immediately reclaimed.
+This is because snapshots can retain data even after it has been "deleted" from the active bucket.
+Ozone now tracks and calculates bucket quotas more clearly to give you an accurate view of your usage.
+
+**How Your Quota is Calculated and Reported**
+
+Your bucket's total reported quota usage is now a sum of both actively used resources and those pending deletion:
+
+*   **Total Reported Used Space:** `usedBytes` (active data) + `pendingDeleteSnapshotBytes` (data pending deletion due to snapshots)
+*   **Total Reported Used Namespace:** `usedNamespace` (active items) + `pendingDeleteSnapshotNamespace` (items pending deletion due to snapshots)
+
+Quota checks and reporting use these comprehensive totals.
+
+**What This Means for You:**
+
+*   **Accurate Quota View:** Your reported bucket quota is more accurate. It includes active data and data held by snapshots, even if deleted from the active view. This prevents a misleading impression of available quota.
+*   **Understanding Space Reclamation:** You'll see that quota is reclaimed only when data is fully purged. This happens after it's no longer held by any snapshot and background cleanup is complete.
+*   **Better Capacity Planning:** This clearer view of quota usage helps in more effective monitoring and capacity planning for your storage.
+