Gets VM RoC

GetChangedBlocks.ps1

#
# This scripts measures the amount of disk change on VMs each time it is run.
# It measures all VM virtual disks for which CBT has been enabled.
#
# The first time it is run, it creatse a file containing baseline data (CBT change IDs and times).
# Each subsequent run measures changes since the baseline was set.
# It supports multiple virtual disks per VM, but not addition of new virtual disks after the baseline is established.
# Note that every run creates a short-lived snapshot on every VM that has CBT enabed.
#
# Time to run will vary in each environment.  In my case, it took about 20 seconds per VM for the 1st run,
# and about half that long for subsequent runs.
#
# To reset the baseline, just delete (or move, or rename) the baseline file and re-run.
#
#
# # Inspired by the VMGuru.com blog posting of August 2011 -- "CBT Tracker Powershell Script - now with more zombie"
# # Re-imagined completely by Carlo.G, February 2016
# # Corrected to call QueryChangedDiskArea repeatedly, May 2016
#


#
# Important literals used in this script
#
$Folder = 'C:\Temp'
$Basefile = 'Baselines.csv'
$Datafile = 'Data.csv'
$vCenter = 'vcenter.domain.tld'
$DTformat = 'yyyy-MM-dd HH:mm:ss' # Chosen to import correctly into Excel
$Creds = Get-Credential  'domain\userid' -Message 'Provide userid\password with permissions on VCenter'
#
# Initialize PowerCLI and connect to vCenter
#
Set-Location "C:\Program Files (x86)\VMware\Infrastructure\vSphere PowerCLI\Scripts"
. .\Initialize-PowerCLIEnvironment.ps1 $true
Connect-VIServer $vcenter  -Credential $creds
 

#
# Get list of VMs with Change Block Tracking (CBT) enabled
#
$Vms = Get-VM | ?{$_.PowerState -eq 'PoweredOn'} | ?{(Get-View $_).Config.ChangeTrackingEnabled}
# Override with a list of specific VM names for testing
# $Vms = @('TEST_VM_1','TEST_VM_2','TEST_VM_3') | % {Get-VM $_}


#
# Exclude  VMs that are sensitive to snapshots
#
$Vms = $VMs | ?{$_.name -notmatch 'HATES_SNAPSHOTS' }
 
#
# Retrieve or generate baseline change ids (one for each disks) for each VM in list to be measured
# Generating a new baseline requires creating a snapshot (which is removed immediately)
#
# Note that there may be more than one disk per VM.
# and in some cases only some disks have CBT enabled.
#
$n = $VMs.count
$i = 0
Write-Host "Getting baselines for $n VMs"
$baselines = @()
Try   {$baselines = Import-CSV (Join-Path $folder $basefile)} 
Catch {Write-Host -f cyan "No $(Join-Path $folder $basefile) file found, so new one will be created"  }
$more = $false
ForEach ($vm in $Vms) {
    ++$i
    $b = $baselines | ?{$vm.name -eq $_.VMname}  | select -first 1
    If ($b -eq $null) {
        Write-Host "Creating baseline for $($vm.name) ($i of $n)"
        $more = $true
        $TimeStamp = Get-Date -format $DTformat
        $snapshot  = New-Snapshot -VM $vm -Name 'Temp for CBT baseline - Delete immediately ' -Description "for Carlo's change block tracking script, $TimeStamp"
        $snapview  = Get-View $snapshot
        $snapdisks = $snapview.Config.Hardware.Device | where {($_.GetType()).Name -eq "VirtualDisk"}   
        ForEach ($d in $snapdisks) {
            [array]$baselines += New-Object 'PSObject' | select `
                @{N='VmName';E={$vm.name}},
                @{N='VmGBProv';E={$vm.ProvisionedSpaceGB}},
                @{N='VmGBUsed';E={$vm.UsedSpaceGB}},
                @{N='DiskSummary';E={$d.deviceinfo.summary}},
                @{N='DiskName';E={$d.deviceinfo.label}},
                @{N='DiskKey';E={$d.key}},
                @{N='TimeStamp';E={$TimeStamp}},
                @{N='ChangeId';E={$d.Backing.ChangeId}}
                }
        Remove-Snapshot $snapshot -Confirm:$false  
        }
    } 
If ($more) {$Baselines | Export-CSV (Join-Path $folder $basefile) -NoTypeInformation -Force}


#
# For each item in Baselines list, measure changes since baseline was set
# A snapshot (which is removed immediately) is needed for each VM measured
# Append results to existing file (if it exists)
#
# Note that there may be more than one disk per VM.
# and in some cases only some disks have CBT enabled.
#
$lastVMname = $null
$snapshot = $null
$data = @()
$Baselines = $BaseLines | Sort VMname, DiskKey | ? {$_.ChangeID -ne '' -and $_.ChangeId -ne $null}
$n = $Baselines.count
$i = 0
ForEach ($b in $Baselines) {
    ++$i
    If ($b.VmName -ne $lastVMname) {
        If ($snapshot -ne $null) {Remove-Snapshot $snapshot -Confirm:$false}
        $LastVmName = $b.VmName
        $vm = Get-VM $b.VmName
        $vmview    = Get-View $vm
        $TimeStamp = Get-Date   -format $DTformat
        $Interval = (New-Timespan $b.TimeStamp $TimeStamp)
        $snapshot  = New-Snapshot -VM $vm -Name 'Temp for CBT polling - Delete immediately ' -Description "for Carlo's change block tracking script, $TimeStamp"
        $snapview  = Get-View $snapshot
        $snapdisks = $snapview.Config.Hardware.Device | where {($_.GetType()).Name -eq "VirtualDisk"} | sort key
        }  
    $disk = $snapdisks | ?{$_.key -eq $b.DiskKey}
    Try {
        $Offset = 0
        $GBChanged = 0
        Do {
            $changes = $VmView.QueryChangedDiskAreas($SnapView.MoRef,$Disk.key,$Offset,$b.ChangeId)
            $GBchanged += ($changes.ChangedArea | % {$_.length} | measure-object -sum).sum/1024/1024/1024
            $LastChange = $changes.changedarea | Sort Start | select -last 1
            $Offset = $LastChange.start + $LastChange.Length
            }
        While ($Disk.CapacityInBytes -gt $Offset -and $Changes.ChangeArea.Count -gt 0) 
        }
    Catch {$GBchanged = 'error'}
    Write-Host "$($b.Vmname) $($b.DiskName) $GBchanged GB changed since $($b.TimeStamp)  ($i of $n)"
    $data += New-Object 'PSObject' | select `
                @{N='VmName';E={$vm.name}},
                @{N='DiskName';E={$disk.deviceinfo.label}},
                @{N='DiskSummary';E={$disk.deviceinfo.summary}},
                @{N='BaseTime';E={$B.TimeStamp}},
                @{N='ThisTime';E={$TimeStamp}},
                @{N='Interval';E={$Interval}},
                @{N='GBChanged';E={$GBChanged}},
                @{N='VmGBProv';E={$vm.ProvisionedSpaceGB}},
                @{N='VmGBUsed';E={$vm.UsedSpaceGB}}
    }
Remove-Snapshot $snapshot -Confirm:$false -EA 0
$Data | Export-CSV (Join-Path $folder $datafile) -NoTypeInformation -Append

                  
#
# Check for left-over CBT-related snapshots
#
Write-Host "Checking for leftover snapshots..."
$Snapshots = Get-VM  | Get-Snapshot | ?{$_.name -match '\sCBT\s'}
If ($snapshots) {
    Write-Host -f red "$(Snapshots.count) left-over CBT snapshots????"
    $Snapshots | ft vm,created,name
    }