Files / Disk Entity

The Files / Disk Entity screen presents the MEASURE Disk Entity which reports statistics at a physical disk volume level.

The Disk Entity provides information on all four possible disk paths (primary, primary backup, mirror and mirror backup) for both the primary and mirror drive.  By default, MOMI consolidates this information into a single line of performance information. The combining of this information can result in percentages of usually up to 200% when mirrored drives are present. For example, if the Write-QBusy-Time is 145%, this effectively means that 72.5% of the time of each disk (145 / 2) is being consumed.  Uncheck the Volume selection to display information in the original or native format as seen below:

In the non-Volume view, the ServerNet Location (Group:Module:Slot) on newer platforms can be used to distinguish between primary and mirror drives.

Detailed disk cache information for a particular entry may be presented in a consolidated window by right-clicking on a disk name and selecting View Disk Entity Detail as seen below.  MEASURE does not provide the same level of detail concerning cache as SCF (hence a few screen differences) and not all disk paths return cache information.

This is an approach to consider when diagnosing disk drive performance issues:

• Drill down starting at the volume level, working down sequentially through the DiskFile, DiskOpen and finally to the process level.

• Starting from the Disk Entity screen, click on a volume and select DiskFile Entity to see all of the active files on the disk.

• On an entry on the DiskFile Entity screen, click to select DiskOpen Entity which displays all of the processes accessing the file.

• On an entry on the DiskOpen screen, click on the Opener Process Name to view Process Detail of the opener process of that file.  (you can also click on the File Name to view the File Entity which provides different I/O counters).