Foreach drive letter array - powershell

Question

I'm putting together a script that checks whether or not a logical drive is USB or an iSCSI target. And if it is ignore the drive letters associated.
Get-WmiObject win32_logicaldisk -Filter "DriveType='3'" |
where-object{$_.DeviceID -ne $usbletters -and $_.DeviceID -ne $iSCSIletters} | %
{$_.Name} | out-file $kreports\avail.txt
My issue is that when multiple drives are detected of the same type they are simply ignored by the not equal to option. I'm assuming I need to do some form of foreach loop?
If someone could point me in the right direction that would be fantastic!
Here's the full script.
#Variables and Arguments
$kreports = "C:\Kworking\reports"
# Create kworking Reports folder
if (!(Test-Path -path $kreports))
{New-Item $kreports -type directory}
# USB Drive check
$diskdrive = gwmi win32_diskdrive | ?{$_.interfacetype -eq "USB"}
$usbletters = $diskdrive | %{gwmi -Query "ASSOCIATORS OF
{Win32_DiskDrive.DeviceID=`"$($_.DeviceID.replace('\','\\'))`"} WHERE
AssocClass = Win32_DiskDriveToDiskPartition"} | %{gwmi -Query "ASSOCIATORS
OF {Win32_DiskPartition.DeviceID=`"$($_.DeviceID)`"} WHERE AssocClass =
Win32_LogicalDiskToPartition"} | %{$_.DeviceID}
# iSCSI Drive check
$iSCSIdrive = gwmi win32_diskdrive | ?{$_.model -match "iSCSI"}
$iSCSIletters = $iSCSIdrive | %{gwmi -Query "ASSOCIATORS OF
{Win32_DiskDrive.DeviceID=`"$($_.DeviceID.replace('\','\\'))`"} WHERE
AssocClass = Win32_DiskDriveToDiskPartition"} | %{gwmi -Query "ASSOCIATORS
OF {Win32_DiskPartition.DeviceID=`"$($_.DeviceID)`"} WHERE AssocClass =
Win32_LogicalDiskToPartition"} | %{$_.DeviceID}
# Disk Information
Get-WmiObject win32_logicaldisk -Filter "DriveType='3'" | where-object{$_.DeviceID -ne
$usbletters -and $_.DeviceID -ne $iSCSIletters} | %{$_.Name} | out-file
$kreports\avail.txt
# Fix Output Line Spacing
$InputFile = "$kreports\avail.txt"
$OutputFile = "$kreports\availdisks.txt"
$Writer = New-Object IO.StreamWriter "$OutputFile"
$Writer.Write( [String]::Join("`r`n", $(Get-Content $InputFile)) )
$Writer.Close()

Answer 1

The problem is that Win32_LogicalDisk's member DeviceID contains drive letter and colon. As the value is, say, C: and you test for equality against C, the where-object doesn't find anything.
Either include the colon on drive letters or use a regexp the Powershell way.
$disks = gwmi win32_logicaldisk -Filter "DriveType='3'"
# Select all devices that do not have deviceids a,b,c,k or l, followed by colon
$avail = $disks | ? { $_.DeviceID -notmatch "[abckl]:"}
# Do something with filtered results