diff --git a/CHANGES.md b/CHANGES.md
index 36f4d273a..423803ad9 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,10 @@ Release Notes.
 
 ## 0.8.0
 
+### Documentation
+
+- Improve the description of the memory in observability doc.
+
 ### Chores
 
 - Fix metrics system typo.
diff --git a/docs/operation/grafana-cluster.json b/docs/operation/grafana-cluster.json
index 18606b8de..39ea54af6 100644
--- a/docs/operation/grafana-cluster.json
+++ b/docs/operation/grafana-cluster.json
@@ -143,7 +143,7 @@
         "type": "prometheus",
         "uid": "${DS_PROMETHEUS}"
       },
-      "description": "The total memory is the total memory available on the system.",
+      "description": "The total memory is the total physical memory available on the system, which means total amount of RAM on the system.",
       "fieldConfig": {
         "defaults": {
           "color": {
diff --git a/docs/operation/observability.md b/docs/operation/observability.md
index b3a928120..6db234ecc 100644
--- a/docs/operation/observability.md
+++ b/docs/operation/observability.md
@@ -40,7 +40,7 @@ The write rate is the number of write operations per second. It is calculated by
 
 #### Total Memory
 
-The total memory is the total memory available on the system.
+The total memory is the total physical memory available on the system, which means total amount of RAM on the system.
 
 **Expression**: `sum(banyandb_system_memory_state{job=~\"$job\", instance=~\"$instance\",kind=\"total\"})`