Update diskstats for linux kernel 4.19 (#1109)

The format of /proc/diskstats is changing in linux-4.19 to include some
additional fields.  See: https://www.kernel.org/doc/Documentation/iostats.txt

* collector/diskstats: use constants for some hard coded strings
* collector/diskstats: update diskstats for linux-4.19
* collector/diskstats: remove kernel doc url from individual metrics

Signed-off-by: Paul Gier <pgier@redhat.com>

5 files changed, 107 insertions, 24 deletions

diff --git a/collector/diskstats_linux.go b/collector/diskstats_linux.go
index 9b86eab..b3d85b1 100644
--- a/collector/diskstats_linux.go
+++ b/collector/diskstats_linux.go
@@ -30,8 +30,9 @@ import (
 )
 
 const (
-        diskSubsystem  = "disk"
-        diskSectorSize = 512
+        diskSubsystem     = "disk"
+        diskSectorSize    = 512
+        diskstatsFilename = "diskstats"
 )
 
 var (
@@ -61,12 +62,12 @@ func init() {
 }
 
 // NewDiskstatsCollector returns a new Collector exposing disk device stats.
+// Docs from https://www.kernel.org/doc/Documentation/iostats.txt
 func NewDiskstatsCollector() (Collector, error) {
         var diskLabelNames = []string{"device"}
 
         return &diskstatsCollector{
                 ignoredDevicesPattern: regexp.MustCompile(*ignoredDevices),
-                // Docs from https://www.kernel.org/doc/Documentation/iostats.txt
                 descs: []typedFactorDesc{
                         {
                                 desc: prometheus.NewDesc(
@@ -79,7 +80,7 @@ func NewDiskstatsCollector() (Collector, error) {
                         {
                                 desc: prometheus.NewDesc(
                                         prometheus.BuildFQName(namespace, diskSubsystem, "reads_merged_total"),
-                                        "The total number of reads merged. See https://www.kernel.org/doc/Documentation/iostats.txt.",
+                                        "The total number of reads merged.",
                                         diskLabelNames,
                                         nil,
                                 ), valueType: prometheus.CounterValue,
@@ -113,7 +114,7 @@ func NewDiskstatsCollector() (Collector, error) {
                         {
                                 desc: prometheus.NewDesc(
                                         prometheus.BuildFQName(namespace, diskSubsystem, "writes_merged_total"),
-                                        "The number of writes merged. See https://www.kernel.org/doc/Documentation/iostats.txt.",
+                                        "The number of writes merged.",
                                         diskLabelNames,
                                         nil,
                                 ), valueType: prometheus.CounterValue,
@@ -156,7 +157,40 @@ func NewDiskstatsCollector() (Collector, error) {
                         {
                                 desc: prometheus.NewDesc(
                                         prometheus.BuildFQName(namespace, diskSubsystem, "io_time_weighted_seconds_total"),
-                                        "The weighted # of seconds spent doing I/Os. See https://www.kernel.org/doc/Documentation/iostats.txt.",
+                                        "The weighted # of seconds spent doing I/Os.",
+                                        diskLabelNames,
+                                        nil,
+                                ), valueType: prometheus.CounterValue,
+                                factor: .001,
+                        },
+                        {
+                                desc: prometheus.NewDesc(
+                                        prometheus.BuildFQName(namespace, diskSubsystem, "discards_completed_total"),
+                                        "The total number of discards completed successfully.",
+                                        diskLabelNames,
+                                        nil,
+                                ), valueType: prometheus.CounterValue,
+                        },
+                        {
+                                desc: prometheus.NewDesc(
+                                        prometheus.BuildFQName(namespace, diskSubsystem, "discards_merged_total"),
+                                        "The total number of discards merged.",
+                                        diskLabelNames,
+                                        nil,
+                                ), valueType: prometheus.CounterValue,
+                        },
+                        {
+                                desc: prometheus.NewDesc(
+                                        prometheus.BuildFQName(namespace, diskSubsystem, "discarded_sectors_total"),
+                                        "The total number of sectors discard successfully.",
+                                        diskLabelNames,
+                                        nil,
+                                ), valueType: prometheus.CounterValue,
+                        },
+                        {
+                                desc: prometheus.NewDesc(
+                                        prometheus.BuildFQName(namespace, diskSubsystem, "discard_time_seconds_total"),
+                                        "This is the total number of seconds spent by all discards.",
                                         diskLabelNames,
                                         nil,
                                 ), valueType: prometheus.CounterValue,
@@ -167,7 +201,6 @@ func NewDiskstatsCollector() (Collector, error) {
 }
 
 func (c *diskstatsCollector) Update(ch chan<- prometheus.Metric) error {
-        procDiskStats := procFilePath("diskstats")
         diskStats, err := getDiskStats()
         if err != nil {
                 return fmt.Errorf("couldn't get diskstats: %s", err)
@@ -179,8 +212,8 @@ func (c *diskstatsCollector) Update(ch chan<- prometheus.Metric) error {
                         continue
                 }
 
-                if len(stats) != len(c.descs) {
-                        return fmt.Errorf("invalid line for %s for %s", procDiskStats, dev)
+                if len(stats) > len(c.descs) {
+                        return fmt.Errorf("invalid line for %s for %s", procFilePath(diskstatsFilename), dev)
                 }
 
                 for i, value := range stats {
@@ -194,8 +227,8 @@ func (c *diskstatsCollector) Update(ch chan<- prometheus.Metric) error {
         return nil
 }
 
-func getDiskStats() (map[string]map[int]string, error) {
-        file, err := os.Open(procFilePath("diskstats"))
+func getDiskStats() (map[string][]string, error) {
+        file, err := os.Open(procFilePath(diskstatsFilename))
         if err != nil {
                 return nil, err
         }
@@ -204,22 +237,19 @@ func getDiskStats() (map[string]map[int]string, error) {
         return parseDiskStats(file)
 }
 
-func parseDiskStats(r io.Reader) (map[string]map[int]string, error) {
+func parseDiskStats(r io.Reader) (map[string][]string, error) {
         var (
-                diskStats = map[string]map[int]string{}
+                diskStats = map[string][]string{}
                 scanner   = bufio.NewScanner(r)
         )
 
         for scanner.Scan() {
                 parts := strings.Fields(scanner.Text())
                 if len(parts) < 4 { // we strip major, minor and dev
-                        return nil, fmt.Errorf("invalid line in %s: %s", procFilePath("diskstats"), scanner.Text())
+                        return nil, fmt.Errorf("invalid line in %s: %s", procFilePath(diskstatsFilename), scanner.Text())
                 }
                 dev := parts[2]
-                diskStats[dev] = map[int]string{}
-                for i, v := range parts[3:] {
-                        diskStats[dev][i] = v
-                }
+                diskStats[dev] = parts[3:]
         }
 
         return diskStats, scanner.Err()
diff --git a/collector/diskstats_linux_test.go b/collector/diskstats_linux_test.go
index 405bf28..84a7de4 100644
--- a/collector/diskstats_linux_test.go
+++ b/collector/diskstats_linux_test.go
@@ -37,4 +37,8 @@ func TestDiskStats(t *testing.T) {
         if want, got := "68", diskStats["mmcblk0p2"][10]; want != got {
                 t.Errorf("want diskstats mmcblk0p2 %s, got %s", want, got)
         }
+
+        if want, got := "11130", diskStats["sdb"][14]; want != got {
+                t.Errorf("want diskstats sdb %s, got %s", want, got)
+        }
 }
diff --git a/collector/fixtures/e2e-64k-page-output.txt b/collector/fixtures/e2e-64k-page-output.txt
index f694567..decad90 100644
--- a/collector/fixtures/e2e-64k-page-output.txt
+++ b/collector/fixtures/e2e-64k-page-output.txt
@@ -290,6 +290,18 @@ node_cpu_seconds_total{cpu="7",mode="softirq"} 0.31
 node_cpu_seconds_total{cpu="7",mode="steal"} 0
 node_cpu_seconds_total{cpu="7",mode="system"} 101.64
 node_cpu_seconds_total{cpu="7",mode="user"} 290.98
+# HELP node_disk_discard_time_seconds_total This is the total number of seconds spent by all discards.
+# TYPE node_disk_discard_time_seconds_total counter
+node_disk_discard_time_seconds_total{device="sdb"} 11.13
+# HELP node_disk_discarded_sectors_total The total number of sectors discard successfully.
+# TYPE node_disk_discarded_sectors_total counter
+node_disk_discarded_sectors_total{device="sdb"} 1.925173784e+09
+# HELP node_disk_discards_completed_total The total number of discards completed successfully.
+# TYPE node_disk_discards_completed_total counter
+node_disk_discards_completed_total{device="sdb"} 68851
+# HELP node_disk_discards_merged_total The total number of discards merged.
+# TYPE node_disk_discards_merged_total counter
+node_disk_discards_merged_total{device="sdb"} 0
 # HELP node_disk_io_now The number of I/Os currently in progress.
 # TYPE node_disk_io_now gauge
 node_disk_io_now{device="dm-0"} 0
@@ -303,6 +315,7 @@ node_disk_io_now{device="mmcblk0p1"} 0
 node_disk_io_now{device="mmcblk0p2"} 0
 node_disk_io_now{device="nvme0n1"} 0
 node_disk_io_now{device="sda"} 0
+node_disk_io_now{device="sdb"} 0
 node_disk_io_now{device="sr0"} 0
 node_disk_io_now{device="vda"} 0
 # HELP node_disk_io_time_seconds_total Total seconds spent doing I/Os.
@@ -318,9 +331,10 @@ node_disk_io_time_seconds_total{device="mmcblk0p1"} 0.024
 node_disk_io_time_seconds_total{device="mmcblk0p2"} 0.068
 node_disk_io_time_seconds_total{device="nvme0n1"} 222.766
 node_disk_io_time_seconds_total{device="sda"} 9653.880000000001
+node_disk_io_time_seconds_total{device="sdb"} 60.730000000000004
 node_disk_io_time_seconds_total{device="sr0"} 0
 node_disk_io_time_seconds_total{device="vda"} 41614.592000000004
-# HELP node_disk_io_time_weighted_seconds_total The weighted # of seconds spent doing I/Os. See https://www.kernel.org/doc/Documentation/iostats.txt.
+# HELP node_disk_io_time_weighted_seconds_total The weighted # of seconds spent doing I/Os.
 # TYPE node_disk_io_time_weighted_seconds_total counter
 node_disk_io_time_weighted_seconds_total{device="dm-0"} 1.206301256e+06
 node_disk_io_time_weighted_seconds_total{device="dm-1"} 0.084
@@ -333,6 +347,7 @@ node_disk_io_time_weighted_seconds_total{device="mmcblk0p1"} 0.024
 node_disk_io_time_weighted_seconds_total{device="mmcblk0p2"} 0.068
 node_disk_io_time_weighted_seconds_total{device="nvme0n1"} 1032.546
 node_disk_io_time_weighted_seconds_total{device="sda"} 82621.804
+node_disk_io_time_weighted_seconds_total{device="sdb"} 67.07000000000001
 node_disk_io_time_weighted_seconds_total{device="sr0"} 0
 node_disk_io_time_weighted_seconds_total{device="vda"} 2.0778722280000001e+06
 # HELP node_disk_read_bytes_total The total number of bytes read successfully.
@@ -348,6 +363,7 @@ node_disk_read_bytes_total{device="mmcblk0p1"} 81920
 node_disk_read_bytes_total{device="mmcblk0p2"} 389120
 node_disk_read_bytes_total{device="nvme0n1"} 2.377714176e+09
 node_disk_read_bytes_total{device="sda"} 5.13713216512e+11
+node_disk_read_bytes_total{device="sdb"} 4.944782848e+09
 node_disk_read_bytes_total{device="sr0"} 0
 node_disk_read_bytes_total{device="vda"} 1.6727491584e+10
 # HELP node_disk_read_time_seconds_total The total number of seconds spent by all reads.
@@ -363,6 +379,7 @@ node_disk_read_time_seconds_total{device="mmcblk0p1"} 0.024
 node_disk_read_time_seconds_total{device="mmcblk0p2"} 0.068
 node_disk_read_time_seconds_total{device="nvme0n1"} 21.650000000000002
 node_disk_read_time_seconds_total{device="sda"} 18492.372
+node_disk_read_time_seconds_total{device="sdb"} 0.084
 node_disk_read_time_seconds_total{device="sr0"} 0
 node_disk_read_time_seconds_total{device="vda"} 8655.768
 # HELP node_disk_reads_completed_total The total number of reads completed successfully.
@@ -378,9 +395,10 @@ node_disk_reads_completed_total{device="mmcblk0p1"} 17
 node_disk_reads_completed_total{device="mmcblk0p2"} 95
 node_disk_reads_completed_total{device="nvme0n1"} 47114
 node_disk_reads_completed_total{device="sda"} 2.5354637e+07
+node_disk_reads_completed_total{device="sdb"} 326552
 node_disk_reads_completed_total{device="sr0"} 0
 node_disk_reads_completed_total{device="vda"} 1.775784e+06
-# HELP node_disk_reads_merged_total The total number of reads merged. See https://www.kernel.org/doc/Documentation/iostats.txt.
+# HELP node_disk_reads_merged_total The total number of reads merged.
 # TYPE node_disk_reads_merged_total counter
 node_disk_reads_merged_total{device="dm-0"} 0
 node_disk_reads_merged_total{device="dm-1"} 0
@@ -393,6 +411,7 @@ node_disk_reads_merged_total{device="mmcblk0p1"} 3
 node_disk_reads_merged_total{device="mmcblk0p2"} 0
 node_disk_reads_merged_total{device="nvme0n1"} 4
 node_disk_reads_merged_total{device="sda"} 3.4367663e+07
+node_disk_reads_merged_total{device="sdb"} 841
 node_disk_reads_merged_total{device="sr0"} 0
 node_disk_reads_merged_total{device="vda"} 15386
 # HELP node_disk_write_time_seconds_total This is the total number of seconds spent by all writes.
@@ -408,6 +427,7 @@ node_disk_write_time_seconds_total{device="mmcblk0p1"} 0
 node_disk_write_time_seconds_total{device="mmcblk0p2"} 0
 node_disk_write_time_seconds_total{device="nvme0n1"} 1011.053
 node_disk_write_time_seconds_total{device="sda"} 63877.96
+node_disk_write_time_seconds_total{device="sdb"} 5.007
 node_disk_write_time_seconds_total{device="sr0"} 0
 node_disk_write_time_seconds_total{device="vda"} 2.069221364e+06
 # HELP node_disk_writes_completed_total The total number of writes completed successfully.
@@ -423,9 +443,10 @@ node_disk_writes_completed_total{device="mmcblk0p1"} 0
 node_disk_writes_completed_total{device="mmcblk0p2"} 0
 node_disk_writes_completed_total{device="nvme0n1"} 1.07832e+06
 node_disk_writes_completed_total{device="sda"} 2.8444756e+07
+node_disk_writes_completed_total{device="sdb"} 41822
 node_disk_writes_completed_total{device="sr0"} 0
 node_disk_writes_completed_total{device="vda"} 6.038856e+06
-# HELP node_disk_writes_merged_total The number of writes merged. See https://www.kernel.org/doc/Documentation/iostats.txt.
+# HELP node_disk_writes_merged_total The number of writes merged.
 # TYPE node_disk_writes_merged_total counter
 node_disk_writes_merged_total{device="dm-0"} 0
 node_disk_writes_merged_total{device="dm-1"} 0
@@ -438,6 +459,7 @@ node_disk_writes_merged_total{device="mmcblk0p1"} 0
 node_disk_writes_merged_total{device="mmcblk0p2"} 0
 node_disk_writes_merged_total{device="nvme0n1"} 43950
 node_disk_writes_merged_total{device="sda"} 1.1134226e+07
+node_disk_writes_merged_total{device="sdb"} 2895
 node_disk_writes_merged_total{device="sr0"} 0
 node_disk_writes_merged_total{device="vda"} 2.0711856e+07
 # HELP node_disk_written_bytes_total The total number of bytes written successfully.
@@ -453,6 +475,7 @@ node_disk_written_bytes_total{device="mmcblk0p1"} 0
 node_disk_written_bytes_total{device="mmcblk0p2"} 0
 node_disk_written_bytes_total{device="nvme0n1"} 2.0199236096e+10
 node_disk_written_bytes_total{device="sda"} 2.58916880384e+11
+node_disk_written_bytes_total{device="sdb"} 1.01012736e+09
 node_disk_written_bytes_total{device="sr0"} 0
 node_disk_written_bytes_total{device="vda"} 1.0938236928e+11
 # HELP node_drbd_activitylog_writes_total Number of updates of the activity log area of the meta data.
diff --git a/collector/fixtures/e2e-output.txt b/collector/fixtures/e2e-output.txt
index 5f0b8ac..a1e3d76 100644
--- a/collector/fixtures/e2e-output.txt
+++ b/collector/fixtures/e2e-output.txt
@@ -290,6 +290,18 @@ node_cpu_seconds_total{cpu="7",mode="softirq"} 0.31
 node_cpu_seconds_total{cpu="7",mode="steal"} 0
 node_cpu_seconds_total{cpu="7",mode="system"} 101.64
 node_cpu_seconds_total{cpu="7",mode="user"} 290.98
+# HELP node_disk_discard_time_seconds_total This is the total number of seconds spent by all discards.
+# TYPE node_disk_discard_time_seconds_total counter
+node_disk_discard_time_seconds_total{device="sdb"} 11.13
+# HELP node_disk_discarded_sectors_total The total number of sectors discard successfully.
+# TYPE node_disk_discarded_sectors_total counter
+node_disk_discarded_sectors_total{device="sdb"} 1.925173784e+09
+# HELP node_disk_discards_completed_total The total number of discards completed successfully.
+# TYPE node_disk_discards_completed_total counter
+node_disk_discards_completed_total{device="sdb"} 68851
+# HELP node_disk_discards_merged_total The total number of discards merged.
+# TYPE node_disk_discards_merged_total counter
+node_disk_discards_merged_total{device="sdb"} 0
 # HELP node_disk_io_now The number of I/Os currently in progress.
 # TYPE node_disk_io_now gauge
 node_disk_io_now{device="dm-0"} 0
@@ -303,6 +315,7 @@ node_disk_io_now{device="mmcblk0p1"} 0
 node_disk_io_now{device="mmcblk0p2"} 0
 node_disk_io_now{device="nvme0n1"} 0
 node_disk_io_now{device="sda"} 0
+node_disk_io_now{device="sdb"} 0
 node_disk_io_now{device="sr0"} 0
 node_disk_io_now{device="vda"} 0
 # HELP node_disk_io_time_seconds_total Total seconds spent doing I/Os.
@@ -318,9 +331,10 @@ node_disk_io_time_seconds_total{device="mmcblk0p1"} 0.024
 node_disk_io_time_seconds_total{device="mmcblk0p2"} 0.068
 node_disk_io_time_seconds_total{device="nvme0n1"} 222.766
 node_disk_io_time_seconds_total{device="sda"} 9653.880000000001
+node_disk_io_time_seconds_total{device="sdb"} 60.730000000000004
 node_disk_io_time_seconds_total{device="sr0"} 0
 node_disk_io_time_seconds_total{device="vda"} 41614.592000000004
-# HELP node_disk_io_time_weighted_seconds_total The weighted # of seconds spent doing I/Os. See https://www.kernel.org/doc/Documentation/iostats.txt.
+# HELP node_disk_io_time_weighted_seconds_total The weighted # of seconds spent doing I/Os.
 # TYPE node_disk_io_time_weighted_seconds_total counter
 node_disk_io_time_weighted_seconds_total{device="dm-0"} 1.206301256e+06
 node_disk_io_time_weighted_seconds_total{device="dm-1"} 0.084
@@ -333,6 +347,7 @@ node_disk_io_time_weighted_seconds_total{device="mmcblk0p1"} 0.024
 node_disk_io_time_weighted_seconds_total{device="mmcblk0p2"} 0.068
 node_disk_io_time_weighted_seconds_total{device="nvme0n1"} 1032.546
 node_disk_io_time_weighted_seconds_total{device="sda"} 82621.804
+node_disk_io_time_weighted_seconds_total{device="sdb"} 67.07000000000001
 node_disk_io_time_weighted_seconds_total{device="sr0"} 0
 node_disk_io_time_weighted_seconds_total{device="vda"} 2.0778722280000001e+06
 # HELP node_disk_read_bytes_total The total number of bytes read successfully.
@@ -348,6 +363,7 @@ node_disk_read_bytes_total{device="mmcblk0p1"} 81920
 node_disk_read_bytes_total{device="mmcblk0p2"} 389120
 node_disk_read_bytes_total{device="nvme0n1"} 2.377714176e+09
 node_disk_read_bytes_total{device="sda"} 5.13713216512e+11
+node_disk_read_bytes_total{device="sdb"} 4.944782848e+09
 node_disk_read_bytes_total{device="sr0"} 0
 node_disk_read_bytes_total{device="vda"} 1.6727491584e+10
 # HELP node_disk_read_time_seconds_total The total number of seconds spent by all reads.
@@ -363,6 +379,7 @@ node_disk_read_time_seconds_total{device="mmcblk0p1"} 0.024
 node_disk_read_time_seconds_total{device="mmcblk0p2"} 0.068
 node_disk_read_time_seconds_total{device="nvme0n1"} 21.650000000000002
 node_disk_read_time_seconds_total{device="sda"} 18492.372
+node_disk_read_time_seconds_total{device="sdb"} 0.084
 node_disk_read_time_seconds_total{device="sr0"} 0
 node_disk_read_time_seconds_total{device="vda"} 8655.768
 # HELP node_disk_reads_completed_total The total number of reads completed successfully.
@@ -378,9 +395,10 @@ node_disk_reads_completed_total{device="mmcblk0p1"} 17
 node_disk_reads_completed_total{device="mmcblk0p2"} 95
 node_disk_reads_completed_total{device="nvme0n1"} 47114
 node_disk_reads_completed_total{device="sda"} 2.5354637e+07
+node_disk_reads_completed_total{device="sdb"} 326552
 node_disk_reads_completed_total{device="sr0"} 0
 node_disk_reads_completed_total{device="vda"} 1.775784e+06
-# HELP node_disk_reads_merged_total The total number of reads merged. See https://www.kernel.org/doc/Documentation/iostats.txt.
+# HELP node_disk_reads_merged_total The total number of reads merged.
 # TYPE node_disk_reads_merged_total counter
 node_disk_reads_merged_total{device="dm-0"} 0
 node_disk_reads_merged_total{device="dm-1"} 0
@@ -393,6 +411,7 @@ node_disk_reads_merged_total{device="mmcblk0p1"} 3
 node_disk_reads_merged_total{device="mmcblk0p2"} 0
 node_disk_reads_merged_total{device="nvme0n1"} 4
 node_disk_reads_merged_total{device="sda"} 3.4367663e+07
+node_disk_reads_merged_total{device="sdb"} 841
 node_disk_reads_merged_total{device="sr0"} 0
 node_disk_reads_merged_total{device="vda"} 15386
 # HELP node_disk_write_time_seconds_total This is the total number of seconds spent by all writes.
@@ -408,6 +427,7 @@ node_disk_write_time_seconds_total{device="mmcblk0p1"} 0
 node_disk_write_time_seconds_total{device="mmcblk0p2"} 0
 node_disk_write_time_seconds_total{device="nvme0n1"} 1011.053
 node_disk_write_time_seconds_total{device="sda"} 63877.96
+node_disk_write_time_seconds_total{device="sdb"} 5.007
 node_disk_write_time_seconds_total{device="sr0"} 0
 node_disk_write_time_seconds_total{device="vda"} 2.069221364e+06
 # HELP node_disk_writes_completed_total The total number of writes completed successfully.
@@ -423,9 +443,10 @@ node_disk_writes_completed_total{device="mmcblk0p1"} 0
 node_disk_writes_completed_total{device="mmcblk0p2"} 0
 node_disk_writes_completed_total{device="nvme0n1"} 1.07832e+06
 node_disk_writes_completed_total{device="sda"} 2.8444756e+07
+node_disk_writes_completed_total{device="sdb"} 41822
 node_disk_writes_completed_total{device="sr0"} 0
 node_disk_writes_completed_total{device="vda"} 6.038856e+06
-# HELP node_disk_writes_merged_total The number of writes merged. See https://www.kernel.org/doc/Documentation/iostats.txt.
+# HELP node_disk_writes_merged_total The number of writes merged.
 # TYPE node_disk_writes_merged_total counter
 node_disk_writes_merged_total{device="dm-0"} 0
 node_disk_writes_merged_total{device="dm-1"} 0
@@ -438,6 +459,7 @@ node_disk_writes_merged_total{device="mmcblk0p1"} 0
 node_disk_writes_merged_total{device="mmcblk0p2"} 0
 node_disk_writes_merged_total{device="nvme0n1"} 43950
 node_disk_writes_merged_total{device="sda"} 1.1134226e+07
+node_disk_writes_merged_total{device="sdb"} 2895
 node_disk_writes_merged_total{device="sr0"} 0
 node_disk_writes_merged_total{device="vda"} 2.0711856e+07
 # HELP node_disk_written_bytes_total The total number of bytes written successfully.
@@ -453,6 +475,7 @@ node_disk_written_bytes_total{device="mmcblk0p1"} 0
 node_disk_written_bytes_total{device="mmcblk0p2"} 0
 node_disk_written_bytes_total{device="nvme0n1"} 2.0199236096e+10
 node_disk_written_bytes_total{device="sda"} 2.58916880384e+11
+node_disk_written_bytes_total{device="sdb"} 1.01012736e+09
 node_disk_written_bytes_total{device="sr0"} 0
 node_disk_written_bytes_total{device="vda"} 1.0938236928e+11
 # HELP node_drbd_activitylog_writes_total Number of updates of the activity log area of the meta data.
diff --git a/collector/fixtures/proc/diskstats b/collector/fixtures/proc/diskstats
index 2457197..b15bf9a 100644
--- a/collector/fixtures/proc/diskstats
+++ b/collector/fixtures/proc/diskstats
@@ -44,3 +44,6 @@
  259       0 nvme0n1 47114 4 4643973 21650 1078320 43950 39451633 1011053 0 222766 1032546
  259       1 nvme0n1p1 1140 0 9370 16 1 0 1 0 0 16 16
  259       2 nvme0n1p2 45914 4 4631243 21626 1036885 43950 39451632 919480 0 131580 940970
+   8       0 sdb 326552 841 9657779 84 41822 2895 1972905 5007 0 60730 67070 68851 0 1925173784 11130
+   8       1 sdb1 231 3 34466 4 24 23 106 0 0 64 64 0 0 0 0
+   8       2 sdb2 326310 838 9622281 67 40726 2872 1972799 4924 0 58250 64567 68851 0 1925173784 11130