change null value to zero in pool dashboard

Change-Id: I1b058d937517e0cdc535399842cb7b81e893254f
Related-Prod: PROD-21427
diff --git a/ceph/files/grafana_dashboards/legacy/ceph_pools_prometheus.json b/ceph/files/grafana_dashboards/legacy/ceph_pools_prometheus.json
index 61e2780..a669b33 100644
--- a/ceph/files/grafana_dashboards/legacy/ceph_pools_prometheus.json
+++ b/ceph/files/grafana_dashboards/legacy/ceph_pools_prometheus.json
@@ -36,7 +36,7 @@
           "lines": true,
           "linewidth": 1,
           "links": [],
-          "nullPointMode": "null",
+          "nullPointMode": "null as zero",
           "percentage": false,
           "pointradius": 5,
           "points": false,
@@ -437,7 +437,7 @@
           "steppedLine": false,
           "targets": [
             {
-              "expr": "avg(irate(ceph_pool_stats_read_op_per_sec{name=\"$pool\"}[3m]))",
+              "expr": "avg(irate(ceph_pool_stats_read_op_per_sec{name=\"$pool\"}[3m])) or absent(avg(irate(ceph_pool_stats_read_op_per_sec{name=\"$pool\"}[3m]))) - 1",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 1,
@@ -446,7 +446,7 @@
               "step": 60
             },
             {
-              "expr": "avg(irate(ceph_pool_stats_write_op_per_sec{name=\"$pool\"}[3m]))",
+              "expr": "avg(irate(ceph_pool_stats_write_op_per_sec{name=\"$pool\"}[3m])) or absent(avg(irate(ceph_pool_stats_write_op_per_sec{name=\"$pool\"}[3m]))) - 1",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 1,
@@ -530,7 +530,7 @@
           "steppedLine": false,
           "targets": [
             {
-              "expr": "avg(irate(ceph_pool_stats_read_bytes_sec{name=\"$pool\"}[3m]))",
+              "expr": "avg(irate(ceph_pool_stats_read_bytes_sec{name=\"$pool\"}[3m])) or absent(irate(ceph_pool_stats_read_bytes_sec{name=\"$pool\"}[3m])) - 1",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 1,
@@ -539,7 +539,7 @@
               "step": 60
             },
             {
-              "expr": "avg(irate(ceph_pool_stats_write_bytes_sec{name=\"$pool\"}[3m]))",
+              "expr": "avg(irate(ceph_pool_stats_write_bytes_sec{name=\"$pool\"}[3m])) or absent(irate(ceph_pool_stats_write_bytes_sec{name=\"$pool\"}[3m])) - 1 ",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 1,
@@ -618,7 +618,7 @@
           "lines": true,
           "linewidth": 1,
           "links": [],
-          "nullPointMode": "null",
+          "nullPointMode": "null as zero",
           "percentage": false,
           "pointradius": 5,
           "points": false,
@@ -696,7 +696,7 @@
           "lines": true,
           "linewidth": 1,
           "links": [],
-          "nullPointMode": "null",
+          "nullPointMode": "null as zero",
           "percentage": false,
           "pointradius": 5,
           "points": false,