#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : DFS Namespace clients get the wrong target or no target at all
    Fix   : Take the dead target out of the namespace
    Source: https://jbtecwiz.com/support/srv-sto-dfs-referral

    Run as     : Elevated PowerShell
    Expect     : 30 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    The path fails entirely for some clients.

    HOW TO UNDO IT
    Set the target state back to Online when the server returns.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 5"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  DFS Namespace clients get the wrong target or no target at all' -ForegroundColor White
Write-Host '  Take the dead target out of the namespace' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   30 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'List the folder targets and their state.' -Command {
    Get-DfsnFolder -Path '\\example.local\Shares\*' | Format-Table Path,State
    Get-DfsnFolderTarget -Path '\\example.local\Shares\Data' | Format-Table TargetPath,State,ReferralPriorityClass
}

Invoke-Step -Number 2 -Do 'Test each target directly to find which is unreachable.' -Why 'DFS keeps offering a target until it is disabled, and a client that is referred to a dead one waits for a timeout before trying another. Disabling it is instant relief for every client.' -Command {
    Get-DfsnFolderTarget -Path '\\example.local\Shares\Data' | ForEach-Object {
      $t = $_.TargetPath
      [PSCustomObject]@{ Target = $t; Reachable = (Test-Path $t) }
    }
}

Invoke-Step -Number 3 -Do 'Disable the failed target rather than deleting it, so it can be re-enabled when the server returns.' -Command {
    Set-DfsnFolderTarget -Path '\\example.local\Shares\Data' -TargetPath '\\fs02\data' -State Offline
}

Invoke-Step -Number 4 -Do 'Check the namespace servers themselves are healthy.' -Command {
    Get-DfsnRootTarget -Path '\\example.local\Shares' | Format-Table TargetPath,State
    dcdiag /test:dfsrevent /v | Select-String 'passed|failed'
}

Invoke-Step -Number 5 -Do 'Reduce the referral time to live if targets change often, so clients recover faster.' -Command {
    Set-DfsnFolder -Path '\\example.local\Shares\Data' -TimeToLiveSec 300
}

Write-Rule "  Confirm it worked"
Show-Prose 'The path opens from every site and only healthy targets are online.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-DfsnFolderTarget -Path '\\example.local\Shares\Data' | Format-Table TargetPath,State
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/srv-sto-dfs-referral' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Set the target state back to Online when the server returns.' 'DarkGray'
Write-Rule