When we create snapshots in VMware environments, we're essentially trading performance for flexibility. The performance impact isn't just about "slower disk I/O" - it's about fundamental changes to the storage stack's behavior.

Here's what happens at the technical level when you create a snapshot:

// Pseudo-code representation of snapshot chain management
class SnapshotChain {
  constructor(baseDisk) {
    this.baseDisk = baseDisk;
    this.deltaDisks = [];
  }

  write(data, block) {
    // New writes go to the delta disk
    const deltaDisk = this.getActiveDelta();
    deltaDisk.write(block, data);
    
    // Metadata updates required
    this.updateBlockMap(block);
  }

  read(block) {
    // Must traverse entire chain to find latest version
    for(let i = this.deltaDisks.length-1; i >= 0; i--) {
      if(this.deltaDisks[i].hasBlock(block)) {
        return this.deltaDisks[i].read(block);
      }
    }
    return this.baseDisk.read(block);
  }
}

Several architectural factors contribute to performance degradation:

1. Read amplification: Each read operation may need to traverse multiple delta disks
2. Write fragmentation: New writes are scattered across delta files rather than contiguous blocks
3. Metadata overhead: The snapshot manager must maintain complex block mapping tables
4. Cache pollution: The storage stack's caching efficiency drops significantly

In our production environment, we measured:

• Limit snapshot chains to 2-3 maximum
• Never run production workloads on snapshots older than 24 hours
• Consider using storage array snapshots instead when possible
• Monitor the "snapshot overhead" metric in vCenter

Here's a PowerCLI snippet we use to enforce snapshot policies:

# PowerShell snippet for snapshot monitoring
Get-VM | Where-Object {$_.PowerState -eq "PoweredOn"} | ForEach-Object {
    $snapshots = Get-Snapshot -VM $_
    if ($snapshots.Count -gt 2) {
        Write-Warning "VM $($_.Name) has $($snapshots.Count) snapshots"
        # Additional automation logic here
    }
    
    # Check snapshot age
    $snapshots | Where-Object {
        (Get-Date) - $_.Created -gt (New-TimeSpan -Days 1)
    } | ForEach-Object {
        Write-Warning "Old snapshot found on $($_.VM): $($_.Name) (Created: $($_.Created))"
    }
}

BaseDisk.vmdk (original disk)
|
└───DeltaDisk1.vmdk (first snapshot)
     |
     └───DeltaDisk2.vmdk (second snapshot)
          |
          └───Current.vmdk (active write layer)

# PowerCLI script to monitor snapshot impact
Get-VM | Where {$_.PowerState -eq "PoweredOn"} | 
Select Name, @{N="SnapshotCount";E={$_.SnapshotCount}}, 
@{N="SnapshotSizeGB";E={[math]::Round(($_.ExtensionData.Snapshot | 
Measure-Object -Property SizeGB -Sum).Sum, 2)}}