diff --git a/cmd/mockbackend/testcases/render_error_all/render_error_all.yaml b/cmd/mockbackend/testcases/render_error_all/render_error_all.yaml
index 133245123..0bc255177 100644
--- a/cmd/mockbackend/testcases/render_error_all/render_error_all.yaml
+++ b/cmd/mockbackend/testcases/render_error_all/render_error_all.yaml
@@ -14,9 +14,9 @@ test:
               httpCode: 200
               contentType: "application/json"
               expectedResults:
-                      - metrics:
-                          - target: "a"
-                            datapoints: [[0,1],[1,2],[2,3],[2,4],[3,5]]
+                  - metrics:
+                      - target: "a"
+                        datapoints: [[0,1],[1,2],[2,3],[2,4],[3,5]]
 
         # empty
         - endpoint: "http://127.0.0.1:8081"
@@ -33,9 +33,9 @@ test:
               httpCode: 200
               contentType: "application/json"
               expectedResults:
-                      - metrics:
-                          - target: "a"
-                            datapoints: [[0,1],[1,2],[2,3],[2,4],[3,5]]              
+                  - metrics:
+                      - target: "a"
+                        datapoints: [[0,1],[1,2],[2,3],[2,4],[3,5]]              
 
         # timeout
         - endpoint: "http://127.0.0.1:8081"
diff --git a/cmd/mockbackend/testcases/render_error_all_rr/carbonapi.yaml b/cmd/mockbackend/testcases/render_error_all_rr/carbonapi.yaml
new file mode 100644
index 000000000..6c7cf2e6e
--- /dev/null
+++ b/cmd/mockbackend/testcases/render_error_all_rr/carbonapi.yaml
@@ -0,0 +1,59 @@
+listen: "localhost:8081"
+expvar:
+  enabled: true
+  pprofEnabled: false
+  listen: ""
+concurency: 1000
+notFoundStatusCode: 200
+cache:
+   type: "mem"
+   size_mb: 0
+   defaultTimeoutSec: 60
+cpus: 0
+tz: ""
+maxBatchSize: 0
+graphite:
+    host: ""
+    interval: "60s"
+    prefix: "carbon.api"
+    pattern: "{prefix}.{fqdn}"
+idleConnections: 10
+pidFile: ""
+upstreams:
+    requireSuccessAll: true
+    buckets: 10
+    timeouts:
+        find: "2s"
+        render: "10s"
+        connect: "200ms"
+    concurrencyLimitPerServer: 0
+    keepAliveInterval: "30s"
+    maxIdleConnsPerHost: 100
+    backendsv2:
+        backends:
+          -
+            groupName: "mock-001"
+            protocol: "auto"
+            lbMethod: "rr"
+            maxTries: 2
+            maxBatchSize: 0
+            keepAliveInterval: "10s"
+            concurrencyLimit: 0
+            forceAttemptHTTP2: true
+            maxIdleConnsPerHost: 1000
+            timeouts:
+                find: "3s"
+                render: "5s"
+                connect: "200ms"
+            servers:
+                - "http://127.0.0.1:9070"
+                - "http://127.0.0.1:9071"
+    graphite09compat: false
+expireDelaySec: 10
+logger:
+    - logger: ""
+      file: "stderr"
+      level: "debug"
+      encoding: "console"
+      encodingTime: "iso8601"
+      encodingDuration: "seconds"
diff --git a/cmd/mockbackend/testcases/render_error_all_rr/render_error_all_rr.yaml b/cmd/mockbackend/testcases/render_error_all_rr/render_error_all_rr.yaml
new file mode 100644
index 000000000..3e9b4c898
--- /dev/null
+++ b/cmd/mockbackend/testcases/render_error_all_rr/render_error_all_rr.yaml
@@ -0,0 +1,137 @@
+version: "v1"
+test:
+    apps:
+        - name: "carbonapi"
+          binary: "./carbonapi"
+          args:
+              - "-config"
+              - "./cmd/mockbackend/testcases/render_error_all_rr/carbonapi.yaml"
+    queries:
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=a&format=json"
+          expectedResponse:
+              httpCode: 200
+              contentType: "application/json"
+              expectedResults:
+                      - metrics:
+                          - target: "a"
+                            datapoints: [[0,1],[1,2],[2,3],[2,4],[3,5]]
+
+        # empty
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=b&format=json"
+          expectedResponse:
+              httpCode: 200
+              contentType: "application/json"
+
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=a&target=b&format=json"
+          expectedResponse:
+            httpCode: 200
+            contentType: "application/json"
+            expectedResults:
+              - metrics:
+                  - target: "a"
+                    datapoints: [[0,1],[1,2],[2,3],[2,4],[3,5]]
+
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=c&format=json"
+          expectedResponse:
+            httpCode: 200
+            contentType: "application/json"
+            expectedResults:
+              - metrics:
+                  - target: "c"
+                    datapoints: [[0,1],[1,2],[2,3],[2,4],[4,5]]
+
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=a&target=b&target=c&format=json"
+          expectedResponse:
+            httpCode: 200
+            contentType: "application/json"
+            expectedResults:
+              - metrics:
+                  - target: "a"
+                    datapoints: [[0,1],[1,2],[2,3],[2,4],[3,5]]
+                  - target: "c"
+                    datapoints: [[0,1],[1,2],[2,3],[2,4],[4,5]]
+
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=divideSeries(a,c)&format=json"
+          expectedResponse:
+            httpCode: 200
+            contentType: "application/json"
+            expectedResults:
+              - metrics:
+                  - target: "divideSeries(a,c)"
+                    tags: {"name": "a"}
+                    datapoints: [[NaN,1],[1,2],[1,3],[1,4],[0.75,5]]
+
+        # 503
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=d&format=json"
+          expectedResponse:
+              httpCode: 503
+              contentType: "text/plain; charset=utf-8"
+
+        # partial success
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=a&target=d&format=json"
+          expectedResponse:
+              httpCode: 503
+              contentType: "text/plain; charset=utf-8"
+
+        # partial success
+        # TODO: must fail, target d failed
+        - endpoint: "http://127.0.0.1:8081"
+          type: "GET"
+          URL: "/render/?target=divideSeries(a,d)&format=json"
+          expectedResponse:
+            httpCode: 503
+            contentType: "text/plain; charset=utf-8"
+
+listeners:
+      - address: ":9070"
+        expressions:
+            "a":
+                pathExpression: "a"
+                emptyBody: true
+                code: 503        
+
+            # 503
+            "c":
+                pathExpression: "c"
+                mptyBody: true
+                code: 503
+
+            "d":
+                pathExpression: "d"
+                emptyBody: true
+                code: 503
+
+      - address: ":9071"
+        expressions:
+            "a":
+                pathExpression: "a"
+                data:
+                    - metricName: "a"
+                      values: [0,1,2,2,3]
+
+            "c":
+                pathExpression: "c"
+                data:
+                    - metricName: "c"
+                      values: [0,1,2,2,4]
+
+            "d":
+                pathExpression: "d"
+                emptyBody: true
+                code: 503
\ No newline at end of file