collector.physical_disk.md

physical_disk collector

The physical_disk collector exposes metrics about physical disks

Metric name prefix	physical_disk
Data source	Perflib
Counters	physicalDisk (Win32_PerfRawData_PerfDisk_physicalDisk)
Enabled by default?	Yes

Flags

--collector.physical_disk.disk-include

If given, a disk needs to match the include regexp in order for the corresponding disk metrics to be reported

--collector.physical_disk.disk-exclude

If given, a disk needs to not match the exclude regexp in order for the corresponding disk metrics to be reported

Metrics

Name	Description	Type	Labels
requests_queued	Number of requests outstanding on the disk at the time the performance data is collected	gauge	disk
read_bytes_total	Rate at which bytes are transferred from the disk during read operations	counter	disk
reads_total	Rate of read operations on the disk	counter	disk
write_bytes_total	Rate at which bytes are transferred to the disk during write operations	counter	disk
writes_total	Rate of write operations on the disk	counter	disk
read_seconds_total	Seconds the disk was busy servicing read requests	counter	disk
write_seconds_total	Seconds the disk was busy servicing write requests	counter	disk
free_bytes	Unused space of the disk in bytes (not real time, updates every 10-15 min)	gauge	disk
size_bytes	Total size of the disk in bytes (not real time, updates every 10-15 min)	gauge	disk
idle_seconds_total	Seconds the disk was idle (not servicing read/write requests)	counter	disk
split_ios_total	Number of I/Os to the disk split into multiple I/Os	counter	disk

Warning about size metrics

The free_bytes and size_bytes metrics are not updated in real time and might have a delay of 10-15min. This is the same behavior as the windows performance counters.

Example metric

Query the rate of write operations to a disk

rate(windows_physical_disk_read_bytes_total{instance="localhost", disk=~"0"}[2m])

Useful queries

Calculate rate of total IOPS for disk

rate(windows_physical_disk_reads_total{instance="localhost", disk=~"0"}[2m]) + rate(windows_physical_disk_writes_total{instance="localhost", disk=~"0"}[2m])

Alerting examples

prometheus.rules

groups:
- name: Windows Disk Alerts
  rules:

  # Sends an alert when disk space usage is above 95%
  - alert: DiskSpaceUsage
    expr: 100.0 - 100 * (windows_physical_disk_free_bytes / windows_physical_disk_size_bytes) > 95
    for: 10m
    labels:
      severity: high
    annotations:
      summary: "Disk Space Usage (instance {{ $labels.instance }})"
      description: "Disk Space on Drive is used more than 95%\n  VALUE = {{ $value }}\n  LABELS: {{ $labels }}"

  # Alerts on disks with over 85% space usage predicted to fill within the next four days
  - alert: DiskFilling
    expr: 100 * (windows_physical_disk_free_bytes / windows_physical_disk_size_bytes) < 15 and predict_linear(windows_physical_disk_free_bytes[6h], 4 * 24 * 3600) < 0
    for: 10m
    labels:
      severity: warning
    annotations:
      summary: "Disk full in four days (instance {{ $labels.instance }})"
      description: "{{ $labels.disk }} is expected to fill up within four days. Currently {{ $value | humanize }}% is available.\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"