# Backup software reports:
Error: VSS_E_WRITERERROR_RETRYABLE (0x800423f3)
The writer experienced a transient error. If the backup
process is retried, the error may not reoccur.

# Windows Event Log:
Log Name:      Application
Source:        VSS
Event ID:      8193
Level:         Error
Description:
Volume Shadow Copy Service error: Unexpected error calling
routine. The writer experienced a transient error.
Error: 0x800423f3, VSS_E_WRITERERROR_RETRYABLE

# Exchange-specific:
Event ID: 2005
Source: MSExchangeRepl
The backup operation has failed with error code 0x800423f3.

# List all VSS writers and their state
vssadmin list writers

# Look for Exchange writers:
# - Microsoft Exchange Writer
# - Microsoft Exchange Replica Writer

# Check for failed writers
vssadmin list writers | Select-String -Pattern "Writer name|State|Last error" -Context 0,2

# Get VSS writer status
$writers = vssadmin list writers
$writers | Select-String -Pattern "Microsoft Exchange" -Context 0,4

# Check for stuck or failed state
# Healthy states: Stable, Waiting for freeze
# Unhealthy: Failed, Unknown

# Get detailed VSS events
Get-EventLog -LogName Application -Source VSS -Newest 20 | Select-Object TimeGenerated, EntryType, Message | Format-List

# Check free space on all volumes
Get-WmiObject Win32_LogicalDisk | Where-Object { $_.DriveType -eq 3 } | Select-Object DeviceID, @{N='FreeGB';E={[math]::Round($_.FreeSpace/1GB,2)}}, @{N='TotalGB';E={[math]::Round($_.Size/1GB,2)}}, @{N='PercentFree';E={[math]::Round(($_.FreeSpace/$_.Size)*100,1)}}

# VSS needs at least 3GB or 10% free space (whichever is greater)
# Exchange databases also need free space for transaction logs

# Check VSS-related services
$services = @(
    "VSS",           # Volume Shadow Copy
    "COMSysApp",     # COM+ System Application
    "MSDTC",         # Distributed Transaction Coordinator
    "MSExchangeIS",  # Exchange Information Store
    "MSExchangeRepl" # Exchange Replication
)

foreach ($svc in $services) {
    $service = Get-Service -Name $svc -ErrorAction SilentlyContinue
    if ($service) {
        Write-Host "$svc : $($service.Status)"$service.Status)"
    } else {
        Write-Host "$svc : Not Found" -ForegroundColor Red
    }
}

# Restart services to reset VSS writer state
Write-Host "Stopping Exchange services..."
Stop-Service MSExchangeRepl -Force
Stop-Service MSExchangeIS -Force

Write-Host "Restarting VSS service..."
Restart-Service VSS -Force

Write-Host "Starting Exchange services..."
Start-Service MSExchangeIS
Start-Service MSExchangeRepl

# Wait for services to stabilize
Start-Sleep -Seconds 30

# Verify writer state
vssadmin list writers | Select-String -Pattern "Microsoft Exchange" -Context 0,4

Write-Host "VSS writers reset. Retry backup."

# List existing shadow copies
vssadmin list shadows

# Delete old shadow copies that may be causing issues
# WARNING: This removes all shadow copies on the volume
vssadmin delete shadows /for=C: /oldest

# Or delete all shadows for a specific volume
# vssadmin delete shadows /for=D: /all

# Resize shadow storage if needed
vssadmin resize shadowstorage /for=D: /on=D: /maxsize=20GB

# List shadow storage settings
vssadmin list shadowstorage

# Paths to exclude from antivirus real-time scanning:

# 1. Exchange Database and Log Paths
$databases = Get-MailboxDatabase | Select-Object Name, EdbFilePath, LogFolderPath
$databases | Format-Table

# 2. Exchange Installation Directory
$exchPath = $env:ExchangeInstallPath
Write-Host "Exchange Install: $exchPath"

# 3. VSS System Path
Write-Host "VSS Path: C:\Windows\System32\LogFiles"

# 4. Cluster paths if DAG
# C:\Windows\Cluster

# Common AV exclusion list for Exchange:
Write-Host ""
Write-Host "Add these exclusions to your antivirus:"
Write-Host "- $exchPath"
$databases | ForEach-Object {
    Write-Host "- $($_.EdbFilePath)"
    Write-Host "- $($_.LogFolderPath)"
}
Write-Host "- C:\Windows\System32\LogFiles\Sum"
Write-Host "- Process: EdgeTransport.exe, Microsoft.Exchange.*.exe"

# Increase VSS timeout via registry
# Default is 60 seconds, increase to 180 for large databases180 for large databases

$registryPath = "HKLM:\Software\Microsoft\Windows NT\CurrentVersion\SPP"
$name = "VssSnapshotTimeout"
$value = 180  # Seconds

# Create or update the value
if (!(Test-Path $registryPath)) {
    New-Item -Path $registryPath -Force
}
Set-ItemProperty -Path $registryPath -Name $name -Value $value -Type DWord

# Also increase Exchange-specific timeout
$exchRegistry = "HKLM:\Software\Microsoft\ExchangeServer\v15\Replay\Parameters"
Set-ItemProperty -Path $exchRegistry -Name "VSSWriterWaitMs" -Value 180000 -Type DWord

Write-Host "VSS timeout increased to 180 seconds. Restart services to apply."

# Check database integrity
$db = Get-MailboxDatabase -Identity "MailboxDB01"
$dbPath = $db.EdbFilePath.PathName

# Run soft recovery (fixes minor issues)
eseutil /r E00 /l "$($db.LogFolderPath)" /d "$($db.EdbFilePath.PathName -replace '\\[^\\]+$')"-replace '\\[^\\]+$')"

# Check database for corruption
eseutil /g "$dbPath" /!10240

# If corruption found, run repair (may lose some data)
# eseutil /p "$dbPath"
# New-MailboxRepairRequest -Database "MailboxDB01" -CorruptionType SearchFolder,ProvisionedFolder,FolderView-Database "MailboxDB01" -CorruptionType SearchFolder,ProvisionedFolder,FolderView

# After any repair, update content index
Update-MailboxDatabaseCopy -Identity "MailboxDB01" -CatalogOnly

# Check VSS writers are stable
$writers = vssadmin list writers
$exchangeWriters = $writers | Select-String -Pattern "Microsoft Exchange" -Context 0,3
$exchangeWriters

# Verify state shows "Stable" not "Failed""Failed"
if ($writers -match "State: \[1\] Stable") {
    Write-Host "Exchange VSS writer is healthy" -ForegroundColor Green
} else {
    Write-Host "Exchange VSS writer may still have issues" -ForegroundColor Yellow
}

# Test VSS with Windows backup
wbadmin start backup -backupTarget:E: -include:D: -vssFull -quiet

# Or trigger backup from your backup software and monitor

# Check Event Log for success
Get-EventLog -LogName Application -Source "MSExchangeRepl" -Newest 10 | Where-Object { $_.Message -like "*backup*" }