PowerShell: How to check for drives with less than 10GB of free diskspace

I’ve been working on a simple PowerShell command today to import into our endpoint management solution so we can alert on disks with low diskspace. It’s been a while since I’ve dabbled with PowerShell, and it reminded me just how flexible it is and much I love it!

So I thought I would walk you through the evolution of the command I ended up with.

Right, on with the tutorial.

First we’ll use the Cmdlet Get-Volume

This has displayed the volumes of the server and associated free diskspace, but the OCD in me needed them ordered neatly so then I ran Get-Volume | Sort-Object DriveLetter to order them by DriveLetter!

Now you can see the tables above shows a SizeRemaining field so we can use this to filter our results.

Type Get-Volume | Where-Object {$_.SizeRemaining -lt 10}

Now you can see our results only show F: as it is an empty CD-ROM, so 10 obviously doesn’t refer to GB. instead it refers to Bytes. So we’ll need to increase the size a little to detect any volumes with less than 10GB remaining.

Type Get-Volume | Where-Object {$_.SizeRemaining -lt 10000000000}

Right now we’re getting somewhere, we can see all volumes on the server with less than 10GB of free diskspace. But I’m not interested in the CD-ROM so let’s filter some more but this time using the DriveType field.

Type Get-Volume | Where-Object {($_.SizeRemaining -lt 10000000000) -and ($_.DriveType -eq “FIXED”)}

Now we’re not really interested in the System Reserved volume either so finally let’s filter this out of our results.

Type Get-Volume | Where-Object {($_.SizeRemaining -lt 10000000000) -and ($_.DriveType -eq “FIXED”) -and ($_.FileSystemLabel -ne “System Reserved”)}

Now one final tweak I’m going to do to make it more readable is convert the Bytes to GB. See the reference section at the end for a description of the math Bytes to GB conversion.

Get-Volume | Where-Object {([math]::truncate($_.SizeRemaining / 1GB) -lt 10)-and ($_.DriveType -eq “FIXED”) -and ($_.FileSystemLabel -ne “System Reserved”)}

$Get-volume where-object math truncate sizeremaining by 1GB is less than 10 and DriveType equals fixed and FileSystemLabel does not equal system reserved$