Powershell script to measure the amount of disk changes on VMware VMs each time it is run.

This scripts measures the amount of disk changes on VMware VMs each time it is run.
The main/original purpose is to get real data of the daily and weekly incremental changes of your
VMs in order to size your data protection / backup solution properly.
It measures all VM virtual disks for which Change Block Tracking (CBT) has been enabled.
The first time it is run, it creates a file containing baseline data (CBT change IDs and times).
Each subsequent run measures changes since the last run.
Additionally once a day/week (first run) it measures changes since the last day/week.
Note that every run creates a short-lived snapshot on every VM that has CBT enabled.

Version:            2.4
Author:             Pasqual Döhring
Creation Date:      2022-01-20
Purpose/Change:     Fixed an issue with different operating system languages. The culture is now set to en-US.
                    Switched to UTF8 encoding for csv exports.
                    Adjusted the Excel spread sheet for the new data format.


Version:            2.3
Author:             Pasqual Döhring
Creation Date:      2022-01-11
Purpose/Change:     Changed the version number to be more consistent with the script name.
                    Fixed a minor bug with the timestamp of snapshots.
                    Created a simple Excel file to analyse the results (_Data_Analysis.xlsx).
                    Added parameter "-FilterScript" to the readme.


Version:            1.2
Author:             Pasqual Döhring
Creation Date:      2021-07-13
Purpose/Change:     Suppress VMware Customer Experience Improvement Program message.
                    Ignore Invalid server certificate warning.
                    New parameter "-OutputJSON". By omitting this switch, the script does not generate normal output. Instead JSON is used as an output at the command line.
                    New parameter "-NoDataFiles". By omitting this switch, the script does not generate any data file output. The base files get still generated since they are needed.
                    Fixed an error when a VM had no disks at all.
                    Got rid of unnecessary steps for VMs that are excluded.
                    Fixed OverFlowException when disks of VMs where too big.
                    Added the possibility to provide vcenter credentials by username and password. (-Username, -Password)
                    VMs can now be excluded by the parameter "-FilterScript". This is based by the properties of a VM (type: VMware.VimAutomation.ViCore.Types.V1.Inventory.VirtualMachine).
                        By using a FilterScript you just include(!) those VMs for which the script is true.
                        Example: -FilterScript '$_.Name -notlike "*test*"'
                        Example: -FilterScript '$_.Name -like "PleaseIncludeMe*" -and $_.PowerState -eq "PoweredOn"'


Version:            1.1
Author:             Pasqual Döhring
Creation Date:      2021-02-11
Purpose/Change:     Added the ability to filter by the datacenter and the cluster of VMware in case you don't want to track the whole vCenter.
                    Datacenter and cluster of each VM are added to the csv files.
                    (Attention: This breaks compatibility with existing Baseline and Data files and increases runtime by roughly 10 percent!)
                    The script now automatically tries to remove leftover snapshots.


Version:            1.0
Author:             Pasqual Döhring
Creation Date:      2021-02-04
Purpose/Change:     This script is based on a script from Carlo Giuliani, Canada, 2016. Thanks a lot for the great work so far!
                    Base script can be found here: (https://www.experts-exchange.com/articles/27059/A-PowerShell-script-to-measure-VM-data-change-rates-using-Changed-Block-Tracking-CBT.html)
                    It is (nearly) a complete rewrite to handle with a lot of things in the old version that I did not like or that did not work well.
                    It can now handle login to the vcenter with single sign on or saved credentials to better work with scripts.
                    It cleans up the generated snapshots nearly all the time.
                    It has a lot more error handling and output of VMs and disks that did not get tracked (e.g. VMs without CBT oder independent disks).
                    It supports the addition of new virtual disks even after the baseline has been established.
                    It keeps track of daily and weekly changes.
                    The code is much more commented and cleaned up (hopefully).
                    If you need to exclude VMs from this script, look for 'Exclude VMs that are sensitive to snapshots' in the script.

Requires VMware PowerCLI to be installed: https://www.vmware.com/support/developer/PowerCLI/

This project on GitHub: https://github.com/turboPasqual/GetChangedBlocksV2

Network name or IP address of the vCenter.
Alias: vc
Mandatory

If the Datacenter gets set, only the VMs inside the given datacenter get tracked.
Alias: dc
Optional

If the Cluster gets set, only the VMs inside the given cluster get tracked.
Alias: dc
Optional

Omit this switch if you want to use single sign on with your windows account to the vCenter.
Alias: sso
Optional

Username to use for the vCenter connection. Must be used in combination with -Password.
Alias: sso
Optional

Plain text password to use for the vCenter connection. Must be used in combination with -Username.
Alias: sso
Optional

Weekday for getting weekly changes. English weekdays.
Optional
Default: Saturday

By omitting this switch, the script does not generate normal output. Instead JSON is used as an output at the command line.
Optional

By omitting this switch, the script does not generate any data file output. The base files get still generated since they are needed.
Optional

VMs can be excluded by this parameter. This is based by the properties of a VM (type: VMware.VimAutomation.ViCore.Types.V1.Inventory.VirtualMachine). By using a FilterScript you just include(!) those VMs for which the script is true.
Optional

GetChangedBlocksV2.ps1 -vCenter vcenter.mycompany.local
Running the script against 'vcenter.mycompany.local' without single sign on.
At first run you are getting asked for credentials which get saved in a credential file for later runs.

GetChangedBlocksV2.ps1 -vCenter vcenter.mycompany.local -SingleSignOn
Running the script against 'vcenter.mycompany.local' with single sign on.

GetChangedBlocksV2.ps1 -vCenter vcenter.mycompany.local -SingleSignOn -weekDay Friday
Running the script against 'vcenter.mycompany.local' with single sign on.
Using Friday as the day to check for the weekly changes.

GetChangedBlocksV2.ps1 -vCenter vcenter.mycompany.local -Datacenter 'MyFancyDatacenter' -Username "domain\admin" -Password "PWD123"
Running the script against 'vcenter.mycompany.local' with explicit user credentials. Using just the VMs inside the datacenter 'MyFancyDatacenter'.

GetChangedBlocksV2.ps1 -vCenter vcenter.mycompany.local -FilterScript '$_.Name -notlike "*test*"'

GetChangedBlocksV2.ps1 -vCenter vcenter.mycompany.local -FilterScript '$_.Name -like "PleaseIncludeMe*" -and $_.PowerState -eq "PoweredOn"'

powershell.exe -File C:\Script\GetChangedBlocksV2.ps1 -vCenter vcenter.loc -FilterScript "$_.Name -notmatch \"importantVM\" -and $_.Name -notlike \"vcenter*\""