Disk I/O service
The Disk I/O service monitors read and write operations on the disk.
Devices running Windows 2000 cannot monitor the Disk I/O service.
| Service Type | WMI |
| Instances on a Device | 16 |
| Supported Systems/Applications | Any WMI-enabled Server - Windows or workstation |
| Device Class | Laptop - Windows, Server - Windows, Workstation - Windows |
| Monitored By | Windows probes |
| Scan Interval | 15 minutes |
| Instance | An instance of the WMI class Win32_PerfRawData_PerDisk_PhysicalDisk; for example, _Total. To find the disk name to monitor, start Perfmon in Windows. Click Add Counters, and in the Performance Object drop-down menus click Physical Disk. The available instances appears in the right hand window under Select instances from list. For Disk Constraint, enter the value contained within the quotations. You must specify a WSP probe as the monitoring endpoint since this is a WMI service. The device class of the device must be Laptop - Windows, Server - Windows or Workstation - Windows. |
Properties queried and calculations performed
| Namespace | root\cimv2 |
| WMI Class | Win32_PerfRawData_PerfDisk_LogicalDisk |
| WMI Property 0 | CurrentDiskQueueLength |
| WMI Property 1 | AvgDiskQueueLength |
| WMI Property 2 | Timestamp_Sys100NS |
| WMI Property 3 | Frequency_Sys100NS |
| Scandetail.1.Recipe | ^scandetail1 / ^timeelapse02 |
Status details
| Status Detail | Description |
|---|---|
| Current Queue | Number of requests outstanding on the disk at the time the performance data is collected, including requests in service at the time of the snapshot. The value represents an instantaneous length, not an average over a time interval. Multi-spindle disk devices can have multiple requests active at one time, but other concurrent requests await service. This property may reflect a transitory high or low queue length. If the disk drive has a sustained load, the value will be consistently high. Requests experience delays proportional to the length of the queue minus the number of spindles on the disks. This difference should average less than two for good performance. |
| Average Queue | The average number of both read and write requests that were queued for the selected disk during the sample interval. |
| Write Operations/Second | The number of write operations performed per second on the selected disk during the sample interval. |
| Read Operations/Second | The number of read operations performed per second on the selected disk during the sample interval. |
| Total Operations/Second | The total number of both read and write operations performed per second on the selected disk during the sample interval. |
| Data Written (KB) | The amount of data written to the selected disk during the sample interval. |
| Data Read (KB) | The amount of data read from the selected disk during the sample interval. |
| Total Data Sent/Received (KB) | The total amount of data both read from and written to the selected disk during the sample interval. |
| Idle Time (%) | The percentage of time during the sample interval in which the selected disk remained in an idle state; all the requests from the operating system to the disk have been completed and there is no pending read or write requests. |
| Disk Time (%) | The average number of both read and write requests that were queued for the selected disk during the sample interval expressed as a percentage. |
| Disk Read Time (%) | The average number of read requests that were queued for the selected disk during the sample interval expressed as a percentage. |