AndrewMorgan.ie

Here’s one that used to bother me alot. The problem usually went as follows:

“Your XenApp servers have very high disk queue’s and IO”

“What’s causing it?”

“dunno…”

With Server 2008, the task manager’s resource monitor feature will help you find these items. But in server 2003 this was a perilous task. The specific details for disk io per process are stored in performance monitor under each specific process running. Trying to analyse each process was a massive pain, but powershell can do some very clever work to help alleviate this!

I wrote two quick functions which act similar to “top” in linux for giving an on screen view, updating at interval of what exactly is creating IO activity. These two functions are:

get-IODataBytes:

Get-IODataOperations

The code for these functions are below:

function get-iodatabytes{
    $result=(get-counter -counter "\Process(*)\IO Data Bytes/sec" -ea 0).countersamples | ? {$_.cookedvalue -gt 0} | select instancename,@{Name="SessionID";Expression={if ($_.path.contains("#")){($_.path.split("#)"))[1]}else{"0"}}},@{Name="IO Data Bytes/sec";Expression={[math]::Round($_.cookedvalue,0)}},@{Name="IO Data KBytes/sec";Expression={[math]::Round($_.cookedvalue / 1024,0)}} | sort -Descending "IO Data Bytes/sec" | ft
    $currentqueue=(((get-counter -counter "\PhysicalDisk(0 C:)\Current Disk Queue Length" -ea 0).countersamples) | select cookedvalue).cookedvalue
    clear
    write-warning "Hit [CTRL] + [C] to exit live capture"
    write-host "Current Disk queue: $currentqueue"
    return $Result
}

FUnction get-IODataOperations {
    $result=(get-counter -counter "\Process(*)\IO Data Operations/sec" -ea 0).countersamples | ? {$_.cookedvalue -gt 0} | select instancename,@{Name="SessionID";Expression={if ($_.path.contains("#")){($_.path.split("#)"))[1]}else{"0"}}},@{Name="IO Data Operations/sec";Expression={[math]::Round($_.cookedvalue,0)}} | sort -Descending "IO Data Operations/sec" | ft
    $currentqueue=(((get-counter -counter "\PhysicalDisk(0 C:)\Current Disk Queue Length" -ea 0).countersamples) | select cookedvalue).cookedvalue
    clear
    write-warning "Hit [CTRL] + [C] to exit live capture"
    write-host "Current Disk queue: $currentqueue"
    return $Result
}

if you wish to loop one of these functions, simply use the following code:

while ($true){
get-iodataoperations
start-sleep 1
}