But on VMTN I got a similar question, and I posted an updated version of the script there.
See https://communities.vmware.com/t5/VMware-PowerCLI-Discussions/get-orphaned-vmdk-information-from-vSAN/m-p/2814645/highlight/true#M98536

Can you try that version and let me know if it returns correct results for you?

– datastore.numberwriteaveraged.average : the metric for a Datastore. Entity is a Datastore.
– disk.numberwriteaveraged.average: the metric for a LUN. Should be equal to the previous one, provided the Datastore is composed of only 1 LUN. Entity is the LUN’s CanonicalName.
– virtualdisk.numberwriteaveraged.average: the metric per VMDK. Entity is the VMDK

If you are interested in meaningfull numbers, specific for a VM, I would use the virtualdisk.numberwriteaveraged.average.

If you want to see if a datastore is over-utilised, I would use the datastore.numberwriteaveraged.average.
If the Datastore is spread over more than 1 LUN, I would also look at disk.numberwriteaveraged.average to check if the issue is due to a specific LUN.

If you want to see the numbers for a 30 min interval, use the Start and Finish parameters on the Get-Stat cmdlet.
Note that due to aggregation the Interval becomes longer, and thus the returned numbers less meaningfull to see/find outliers.

Hope this helps.

disk.numberwriteaveraged.average
virtualdisk.numberwriteaveraged.average
datastore.numberwriteaveraged.average

Check this out:

(get-vm VM01 | Get-Stat -Stat datastore.numberwriteaveraged.average -Start (Get-Date).AddMinutes(-30) -IntervalMins 1 | Measure-Object Value -Average).Average
122.188888888889

(get-vm VM01 | Get-Stat -Stat disk.numberwriteaveraged.average -Start (Get-Date).AddMinutes(-30) -IntervalMins 1 | Measure-Object Value -Average).Average
121.644444444444

(get-vm VM01 | Get-Stat -Stat virtualdisk.numberwriteaveraged.average -Start (Get-Date).AddMinutes(-30) -IntervalMins 1 | Measure-Object Value -Average).Average
10.9333333333333

I want the average write IOPS of some VM in the last 30 minutes.
Datastore? Disk? VirtualDisk?

Another possible cause I can think of is that due to the default MaxSamples of 100 some recent Tasks are not included.
You might want to use that parameter to give it a try.


Get-TaskPlus -Start $start -Realtime -MaxSamples ([int]::MaxValue)


Name Port User
—- —- —-
vca07.pollaio.lan 443 CORP.LOCAL\Administrator

PS C:\Users\fabio.storni>
PS C:\Users\fabio.storni> $si = Get-View ServiceInstance
$taskMgr = Get-View $si.Content.TaskManager

if($taskMgr.RecentTask.Count -ne 0){
Get-View $taskMgr.RecentTask
}
else {
Write-Host “No recent Tasks”
}
No recent Tasks
PS C:\Users\fabio.storni>

The tasks that I want check are MOVE-VM with RUNASYNC

if($taskMgr.RecentTask.Count -ne 0){
Get-View $taskMgr.RecentTask
}
else {
Write-Host "No recent Tasks"
}