rrd stats: improve io delay stats

src/api2/admin/datastore.rs

@@ -875,8 +875,9 @@ fn get_rrd_stats(
         &rrd_dir,
         &[
             "total", "used",
-            "read_ios", "read_bytes", "read_ticks",
-            "write_ios", "write_bytes", "write_ticks",
+            "read_ios", "read_bytes",
+            "write_ios", "write_bytes",
+            "io_ticks",
         ],
         timeframe,
         cf,

src/api2/node/rrd.rs

@@ -36,8 +36,9 @@ fn get_node_stats(
             "netin", "netout",
             "loadavg",
             "total", "used",
-            "read_ios", "read_bytes", "read_ticks",
-            "write_ios", "write_bytes", "write_ticks",
+            "read_ios", "read_bytes",
+            "write_ios", "write_bytes",
+            "io_ticks",
          ],
         timeframe,
         cf,