From 6fb7d2883d4309d37aa13618897de4729554c67a Mon Sep 17 00:00:00 2001
From: Cameron Sparr <cameronsparr@gmail.com>
Date: Wed, 2 Dec 2015 12:44:16 -0700
Subject: [PATCH] io plugin, add an 'unknown' tag when the serial number can't
 be found

closes #405
---
 CHANGELOG.md           |  9 +++++++++
 plugins/system/disk.go | 18 ++++++++++--------
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a85e0aef8..08a390994 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,12 @@
+## v0.2.4 [unreleased]
+
+### Features
+- [#412](https://github.com/influxdb/telegraf/pull/412): Additional memcached stats. Thanks @mgresser!
+- [#410](https://github.com/influxdb/telegraf/pull/410): Additional redis metrics. Thanks @vlaadbrain!
+
+### Bugfixes
+- [#405](https://github.com/influxdb/telegraf/issues/405): Prometheus output cardinality issue
+
 ## v0.2.3 [2015-11-30]
 
 ### Release Notes
diff --git a/plugins/system/disk.go b/plugins/system/disk.go
index 784dcdb13..2e202f8d2 100644
--- a/plugins/system/disk.go
+++ b/plugins/system/disk.go
@@ -73,12 +73,12 @@ func (_ *DiskIOStats) Description() string {
 }
 
 var diskIoSampleConfig = `
-  # By default, telegraf will gather stats for all devices including 
+  # By default, telegraf will gather stats for all devices including
   # disk partitions.
   # Setting devices will restrict the stats to the specified devcies.
-  # Devices=["sda","sdb"]
+  # devices = ["sda","sdb"]
   # Uncomment the following line if you do not need disk serial numbers.
-  # SkipSerialNumber = true
+  # skip_serial_number = true
 `
 
 func (_ *DiskIOStats) SampleConfig() string {
@@ -106,11 +106,13 @@ func (s *DiskIOStats) Gather(acc plugins.Accumulator) error {
 			continue
 		}
 		tags := map[string]string{}
-		if len(io.Name) != 0 {
-			tags["name"] = io.Name
-		}
-		if len(io.SerialNumber) != 0 && !s.SkipSerialNumber {
-			tags["serial"] = io.SerialNumber
+		tags["name"] = io.Name
+		if !s.SkipSerialNumber {
+			if len(io.SerialNumber) != 0 {
+				tags["serial"] = io.SerialNumber
+			} else {
+				tags["serial"] = "unknown"
+			}
 		}
 
 		acc.Add("reads", io.ReadCount, tags)