Sunday, August 2, 2020

Powershell: VMWare vCenter Standard, Move all VM from a host and place it in maintenance mode

I have VMWare vCenter standard edition, and there is a limitation with placing the server in maintenance mode, as it will never complete unless you move all the VM from that host to another host and then place the server in maintenance mode. something I really don't like, its a small basic regular thing any admin need to do, maybe updating the server or whatever.
When it comes to manual work (which I hate so much), you will need to distribute your VMs based on the host which has more free memory and also healthy. the challenge I have is I have about 30 servers all running the standard edition, and I need to update the hosts, so redistribute the load and check which server has more memory, and Bla Bla Bla, of boring things, so I got the idea to automate this.
The below script (can be downloaded from here too) will do the following:
  • Import the VMWare module and connect to the VI Server.
  • Get a list of all the VM in the host that should be placed in maintenance mode.
  • for each virtual machine, find the proper server to place it (based on the most server which has the freest memory).
  • Redistribute the load.
    • if no server is available with enough memory to have the VM, the script will let you know and won't overcommit your servers, unless you want so.
  • After all is done, will provide you with a basic report about each VM, the old host, and the new host.
  • place the server in maintenance mode.
Parameter and Overcommit prevention
The script requires some parameter to be filled before it can do the magic:
  • FromVMHostName: The name of the server you want to move the VM from and place it in maintenance mode, Please Note that the server name should be exactly as the one registered in your vCenter, so if you are using FQDN, pass it here too.
  • MaxMemAllowed: The Percentage of the total free memory of the destination server before being excluded from the selection, the default value is 80, so no VM will be shipped to any server which has more than 80 percent of utilized memory.
  • vCenter: your vCenter IP or name
  • FromCluster: the cluster you want to search through
Usage and Execution

Set-AutoEMM.ps1 -FromVMHostName myserver.domain.local -MaxMemAllowed 80 -FromCluster Production

The above line will get all the VMs from myserver.domain.local and distribute them to all hosts in the same cluster which has less than 80 percent utilized memory.

What if and during the migration the servers get utilized more than 80 percent?

Well, the script will evaluate the server before and after each VM being moved and do the proper calculation, so before moving the VM the script will calculate and check if the destination server will be over 80 percent, it will be excluded from being a destination for the migration. If no more hosts are available with less than 80 percent memory utilization (or whatever the value you set in the MaxMemAllowed ), the script will fail and stop, surely it will display something on the screen telling that no more hosts available.

Hope you enjoy this script and find it useful, please let me know by commenting or dropping me a message farisnt@gmail.com

If you notice any bug or issue, let me know :)



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<# .Description
    Function To Move VMs From 1 host to other 
    It Depend on the host Memory availibilty 
    .Example
    Set-AutoEMM.ps1 -FromVMHostName MyVMHostServer -MaxMemAllowed 80 -FromCluster Production
    -FromVMHostName: The Source VMHost Server
    -MaxMemAllowed: Percentage of memory limit, default is 80, if the server memory load is 80% or more VMs wont be moved to this server
                    and the script will search for another server to move the VM to
                    if there is no more available server with less than 80% or the required value, the script will stop and show an error
                    indicating the failure.
    -FromCluster: Cluster name where the hosts are exist
    This Script is for free you can update and use it as you want, Please add your name under the contributor
    Created By: 
     -Faris Malaeb
    Contributor
    #Requires -Modules VMware.VimAutomation.Core
#>
param (
	[parameter(mandatory = $True)]
	$FromVMHostName ,
	[parameter(mandatory = $False)]
	[int]$MaxMemAllowed = "80",
	[parameter(mandatory = $True)]
	$vCenter ,
	[parameter(mandatory = $True)]
	$FromCluster 
)

################# General Variables
$Finalresult=@()
[bool]$ErrorFlag=$False
##########
########## Required module
Import-Module VMware.VimAutomation.Core
###############

Function Get-MostFreeServer ($NeededMemorySizeinGB) {

        #Below I will get the list of VMHost which are applicable for migration which include the following filter
          #Excluding the Move From Server
          #Server with a proper state
          # Have enough memory that match the user input parameter
    $CurrentServersLoad=Get-VMHost |  where{ ($_.name -notlike $FromVMHostName) -and ($_.ConnectionState -notlike "*main*") -and ($_.ConnectionState -notlike "NotResponding") -and ($_.ConnectionState -notlike "Unknown") -and ((($_.MemoryUsageGB + $NeededMemorySizeinGB)/$_.MemoryTotalGB * 100) -lt $MaxMemAllowed) } | Sort-Object MemoryUsageGB  
    if (($CurrentServersLoad).count -lt 1){ Write-Host "I am sorry, but there is no space for any migration..."
    # No Server available to hold the migration
    return "PS_FAIL_No_Resource"
    }
    Else{
    #Yes there are at least one server that is good to host the VM Migration.
    return $CurrentServersLoad[0].Name
    }   

}
#Checking the MaxMemAllowed User input to make sure that the user type a proper value
Write-Host "Validating the input" -ForegroundColor Yellow
if (($MaxMemAllowed -le 5) -or ($MaxMemAllowed -gt 99)){
Write-Host "I am sorry, but it seems that the MaxMemAllowed is not correct" -ForegroundColor Red
Write-Host "The MaxMemAllowed cannot be as "$MaxMemAllowed -ForegroundColor Red
break
}


Try
{
	
	if ($global:DefaultVIServer.count -eq 0)
	{
		#If No Connection to VC found then the script will start a new connection, otherwise the -vCenter Parameter is ignored
		write-host "Please Connect to vCenter using Connect-VIServer first" -ForegroundColor Yellow
		$VC = Get-Credential -Message "Please type the username and password for vCenter" -ea Stop -UserName "administrator@vsphere.local"
		if ($VC -eq $null) { Write-Host -ForegroundColor Red "User press Cancel, I am leaving ..."; exit }
		Connect-VIServer -Credential $VC -Server $vCenter -ErrorAction Stop
		
	}
	
	Write-Host "Getting a list of VMs in host "$FromVMHostName -ForegroundColor Yellow
	#Get a list of VM on the server that should be migrated. only powered on VM.. I dont care about powered off VM
	$VMsInHost = Get-VMHost $FromVMHostName -ErrorAction Stop | Get-VM | where{ $_.PowerState -like "*On" }
	Write-Host "Total Number of VM to move is:"$VMsInHost.Count -ForegroundColor Yellow
	Foreach ($SingleVM in $VMsInHost){
        #Creating an Object to store the progress report
	    $VMnewLocation=new-object PSObject
        $VMnewLocation | Add-Member -NotePropertyName "VM Name" -NotePropertyValue $SingleVM.Name
        $VMnewLocation | Add-Member -NotePropertyName "Old Host" -NotePropertyValue $SingleVM.VMHost
        
		Write-host "Parsing VM " $SingleVM.Name -ForegroundColor Yellow
        #Call the function to get a list of possible servers to move the VM to.
        $Migrate=Get-MostFreeServer -NeededMemorySizeinGB $SingleVM.MemoryGB
        #PS_FAIL_No_Resource is a custom message will return from the function incase there is no available server to host the VM Migration.
            if ($Migrate -notlike "PS_FAIL_No_Resource"){
                Write-Host "Moving "$SingleVM "to "$Migrate ",Please wait a few seconds" -ForegroundColor Yellow
                #Move the VM
                Move-VM -VM $SingleVM -Destination $Migrate -ErrorAction Stop
                sleep -Seconds 1
                $VMnewLocation | Add-Member -NotePropertyName "New Host" -NotePropertyValue ((get-vm $SingleVM).vmhost.Name)
                Write-Host $SingleVM "is now in the following host" $VMnewLocation.'New Host' -ForegroundColor Yellow
                $Finalresult+=$VMnewLocation 
            }
		    Else {
                    #No available server, the following message will be displayed.
                Write-Host "It seems there is no more servers to move the load, you can change the value of the MaxMemAllowed to allow more load... Nothing more to do." -ForegroundColor Red
                Write-Host "I cannot move "$SingleVM
                Write-Host "final report is:"
                $Finalresult
                $ErrorFlag=$true
                return
                }
    }
}



Catch [exception]{
# Any unexpected error will return here and stop the script execution.
	Write-Host $_.Exception.message -ForegroundColor Red
    $ErrorFlag=$true
    break

}

Finally{
        #Checking the server is any more VM on it, if there is no VM, then place the server in maintenance Mode
        #Else, there should be an error indicating what is going on.
        if ($ErrorFlag -notlike $true){
            if ((Get-VM | where{ ($_.host -like $FromVMHostName) -and ($_.PowerState -like "*on")}).count -eq 0) { 
                Write-Host "All Done, will place the server in maintenance mode" -ForegroundColor Yellow
                Set-VMHost $FromVMHostName -State Maintenance
                Get-VMHost $FromVMHostName
                $Finalresult | ft
            }
            if ((Get-VM | where{ ($_.host -like $FromVMHostName) -and ($_.PowerState -like "*on")}).count -gt 0) { 
                 Write-Host "It seems that VM Migration not completed. maybe some resource issue"
                 $Finalresult | ft
            }
        }
}

#Use it on your own risk.
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