Disk Latency information from cdm probe looks incorrect
Article ID: 92324
Updated On:
Products
DX Unified Infrastructure Management (Nimsoft / UIM)
Issue/Introduction
Looking at the Disk Latency information monitored by the cdm probe on a Windows system, the Disk Write Latency and Total Latency values look too similar. Is this expected?
Environment
UIM cdm any version
Resolution
The Total Latency value is not a sum of Disk Read and Disk Write Latency. It represents the total latency of the disk and it is not unusual for it to look similar to the Disk Write Latency.
On Windows servers the cdm probe relies on Windows performance counters for disk latency information.
The performance counters are mapped as follows:
Total Latency (QOS_DISK_LATENCY) > PhysicalDisk Object\Avg. Disk sec/Transfer
Disk Read Latency (QOS_DISK_READ_LATENCY) > PhysicalDisk Object\Avg. Disk sec/Read
Disk Write Latency (QOS_DISK_WRITE_LATENCY) > PhysicalDisk Object\Avg. Disk sec/Write
The probe relies on numbers provided by the Operating System, these are not calculated by the probe.
On Windows servers the cdm probe relies on Windows performance counters for disk latency information.
The performance counters are mapped as follows:
Total Latency (QOS_DISK_LATENCY) > PhysicalDisk Object\Avg. Disk sec/Transfer
Disk Read Latency (QOS_DISK_READ_LATENCY) > PhysicalDisk Object\Avg. Disk sec/Read
Disk Write Latency (QOS_DISK_WRITE_LATENCY) > PhysicalDisk Object\Avg. Disk sec/Write
The probe relies on numbers provided by the Operating System, these are not calculated by the probe.
Additional Information
The following URL contains a list and description of the PhysicalDisk Object performance counters.
https://msdn.microsoft.com/en-us/library/ms804035.aspx
https://msdn.microsoft.com/en-us/library/ms804035.aspx
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