Performance history for drives
This sub-topic of Performance history for Storage Spaces Direct describes in detail the performance history collected for drives. Performance history is available for every drive in the cluster storage subsystem, regardless of bus or media type. However, it is not available for OS boot drives.
Note
Performance history cannot be collected for drives in a server that is down. Collection will resume automatically when the server comes back up.
Series names and units
These series are collected for every eligible drive:
| Series | Unit |
|---|---|
physicaldisk.iops.read |
per second |
physicaldisk.iops.write |
per second |
physicaldisk.iops.total |
per second |
physicaldisk.throughput.read |
bytes per second |
physicaldisk.throughput.write |
bytes per second |
physicaldisk.throughput.total |
bytes per second |
physicaldisk.latency.read |
seconds |
physicaldisk.latency.write |
seconds |
physicaldisk.latency.average |
seconds |
physicaldisk.size.total |
bytes |
physicaldisk.size.used |
bytes |
How to interpret
| Series | How to interpret |
|---|---|
physicaldisk.iops.read |
Number of read operations per second completed by the drive. |
physicaldisk.iops.write |
Number of write operations per second completed by the drive. |
physicaldisk.iops.total |
Total number of read or write operations per second completed by the drive. |
physicaldisk.throughput.read |
Quantity of data read from the drive per second. |
physicaldisk.throughput.write |
Quantity of data written to the drive per second. |
physicaldisk.throughput.total |
Total quantity of data read from or written to the drive per second. |
physicaldisk.latency.read |
Average latency of read operations from the drive. |
physicaldisk.latency.write |
Average latency of write operations to the drive. |
physicaldisk.latency.average |
Average latency of all operations to or from the drive. |
physicaldisk.size.total |
The total storage capacity of the drive. |
physicaldisk.size.used |
The used storage capacity of the drive. |
Where they come from
The iops.*, throughput.*, and latency.* series are collected from the Physical Disk performance counter set on the server where the drive is connected, one instance per drive. These counters are measured by partmgr.sys and do not include much of the Windows software stack nor any network hops. They are representative of device hardware performance.
| Series | Source counter |
|---|---|
physicaldisk.iops.read |
Disk Reads/sec |
physicaldisk.iops.write |
Disk Writes/sec |
physicaldisk.iops.total |
Disk Transfers/sec |
physicaldisk.throughput.read |
Disk Read Bytes/sec |
physicaldisk.throughput.write |
Disk Write Bytes/sec |
physicaldisk.throughput.total |
Disk Bytes/sec |
physicaldisk.latency.read |
Avg. Disk sec/Read |
physicaldisk.latency.write |
Avg. Disk sec/Writes |
physicaldisk.latency.average |
Avg. Disk sec/Transfer |
Note
Counters are measured over the entire interval, not sampled. For example, if the drive is idle for 9 seconds but completes 30 IOs in the 10th second, its physicaldisk.iops.total will be recorded as 3 IOs per second on average during this 10-second interval. This ensures its performance history captures all activity and is robust to noise.
The size.* series are collected from the MSFT_PhysicalDisk class in WMI, one instance per drive.
| Series | Source property |
|---|---|
physicaldisk.size.total |
Size |
physicaldisk.size.used |
VirtualDiskFootprint |
Usage in PowerShell
Use the Get-PhysicalDisk cmdlet:
Get-PhysicalDisk -SerialNumber <SerialNumber> | Get-ClusterPerf