Monitoring with PowerShell: Monitoring NAS devices

This was actually requested a couple of times but I’ve always seem to hold off on it, mostly because we don’t use that many NAS devices anymore. I did decide to make it a bit more universal than just NAS devices really – It’s about monitoring any device that has SSH access and of which you know the commands that you need. I’ve just used NAS’s as an example in this case.

We’re using SSH because most NAS devices support it – e.g. QNAP/Synology/etc. I like this method more than SNMP monitoring because I strongly believe more in agent based monitoring than SNMP probing.

So lets get started.

The Script

The script itself is very straight-forward; we download the SSH-Posh module by Carlos Perez and then connect to the NAS using SSH, we execute our command defined in $Command. In the case of most NAS devices you can use the command “cat /proc/mdstat”. After executing this command we compare if it contains any words we don’t like, such as fail, rebuild, recovery, etc. 🙂

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$Command = 'cat /proc/mdstat'
$NotHealthyStates = "*recovery*", "*failed*", "*failure*", "*offline*", "*rebuilding*"
$DeviceIP = 'YOURRDEVICEIP OR HOSTNAME'
$Creds = Get-Credential #Replace this with your RMMs method to handle credentials.

If (Get-Module -ListAvailable -Name "Posh-SSH") { Import-module "Posh-SSH" } Else { install-module "Posh-SSH" -Force; import-module "Posh-SSH" }

try {
$null = New-SSHSession -ComputerName $DeviceIP -Credential $Creds -AcceptKey -force
    $SSHOutput = (Invoke-SSHCommand -Index 0 -Command $command).output
    $null = Get-SSHSession | Remove-SSHSession
}
catch {
    write-host "Unhealthy - Could not connect to SSH."
    break
}
if (!$SSHOutput) { write-host "Unhealthy - No SSH output found" ; break }

$HealthState = foreach ($State in $NotHealthyStates) {
    if ($SSHOutput -like $State) {
"Unhealthy - $State found."
}
}

if (!$HealthState) { write-host "Healthy - No issues found." } else { write-host $HealthState }

And that’s it! as always, Happy PowerShelling. 🙂