When working with VMware ESXi 5, you might encounter a critical limitation where snapshot operations fail with the message: "This virtual machine has 255 or more redo logs in a single branch of its snapshot tree". This occurs when delta files accumulate beyond VMware's design limit.

The VM folder typically contains these problematic files:

myvm-000001-delta.vmdk
myvm-000002-delta.vmdk
...
myvm-000255-delta.vmdk

Each represents a generation of changes since the last snapshot or consolidation.

When the GUI consolidation fails, we need to intervene at the filesystem level:

1. SSH into the ESXi host
2. Navigate to the VM directory:

cd /vmfs/volumes/[datastore-name]/[vm-folder]

3. List all delta files:

ls -la *-delta.vmdk

For Windows administrators, this PowerCLI script can help identify affected VMs:

Connect-VIServer -Server your_esxi_host
Get-VM | Where { $_.ExtensionData.LayoutEx.File | 
    Where { $_.Name -like "*-delta.vmdk" } | 
    Measure-Object | Select -ExpandProperty Count } -GE 255

When all else fails, consider these steps:

1. Power off the VM
2. Clone to new VM using vmkfstools:

vmkfstools -i problematic.vmdk new_clean.vmdk -d thin

3. Create new VM configuration pointing to the cloned disks

• Implement regular snapshot monitoring
• Set up alerts for delta file counts exceeding 200
• Consider alternative backup methods that don't rely on snapshots

Before deleting any files:

• Take a complete backup
• Document the original file structure
• Verify VM power state (must be powered off for safe operations)

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When working with VMware ESXi 5, you might encounter a scenario where snapshot creation fails, and the VM summary page shows a warning about disk consolidation. Attempting to consolidate snapshots results in an error stating: "This virtual machine has 255 or more redo logs in a single branch of its snapshot tree. The maximum supported limit has been reached...".

VMware ESXi 5 has a hard limit of 255 redo logs (delta files) per VM snapshot chain. When this threshold is reached, further snapshots or consolidations are blocked. This typically occurs due to:

• Long-running snapshots left unattended.
• Failed backup jobs that didn't clean up temporary snapshots.
• Manual snapshot operations that were interrupted.

In the VM's datastore, you’ll see files like:

myvm-000255-ctk.vmdk  
myvm-000255-delta.vmdk  
myvm-000255.vmdk  

These files indicate an overflow in the snapshot chain.

If the GUI fails, SSH into the ESXi host and use these commands:

# List all snapshots (even hidden ones)  
vim-cmd vmsvc/get.snapshotinfo [VMID]  

# Force consolidation (replace [VMID] with your VM's ID)  
vim-cmd vmsvc/snapshot.consolidate [VMID]  

Warning: Only proceed if you have verified no critical snapshots exist. Navigate to the VM’s directory on the datastore and delete redundant delta files (e.g., myvm-000255-delta.vmdk). Then:

# Re-register the VM  
vim-cmd solo/registervm /vmfs/volumes/[DATASTORE]/[VM_FOLDER]/[VM_NAME].vmx  

• Regularly monitor snapshots using esxcli storage vmfs snapshot list.
• Automate snapshot cleanup in backup scripts.
• Upgrade to a newer ESXi version (6.0+ handles this better).

For automated cleanup, use this PowerCLI snippet:

Connect-VIServer -Server your_esxi_host  
$vm = Get-VM -Name "myvm"  
$snapshots = Get-Snapshot -VM $vm  
if ($snapshots.Count -gt 0) {  
  Remove-Snapshot -Snapshot $snapshots[0] -Confirm:$false  
}  
Disconnect-VIServer -Server * -Force