12 Replies Latest reply on May 20, 2019 9:23 AM by ndnguyen

Listing all snapshots per vm using get-view

Marco_2_G May 23, 2018 4:48 AM

Hi everyone

I am in the process of developing a script to cleanup after our backup software.

One of the tasks will be to find snapshots of a certain name and remove them. This is pretty straight forward.

However, since we have several vCenters linked and since, when a backup job dies, there can be quite a number of of snapshots to work through AND people sometimes don't notice for a few days that something was amiss, I would like to optimise this in a few key aspects:

When a vm has nothing but backup snaps to be deleted, I would like to tell it to delete them all at once, which should be way easier than doing one at a time.

To do that, I need to check all snapshots per vm and group the vms and or their snapshots into either the "delete all" category or the "delete individually" category.

I would like to use views to drill down the data and only work with objects when it is clear what has to be done where. For this I need a way to find all snapshots of a certain vm. I have no trouble finding all vms with snapshots but I have so far only found a way to find the active snapshot and the root snapshot.

I can of course traverse the snapshot chains in code but I find this rather inelegant...

So in short: Is there a quick way in get-view to find all snapshots belonging to a vm? Or is there a much easier way to do what I want in the first place?

Regards,

Marco

1. Re: Listing all snapshots per vm using get-view

LucD May 23, 2018 5:18 AM (in response to Marco_2_G)

The fastest way to find VMs with snapshot is something like this

Get-View -ViewType VirtualMachine -Property Name,Snapshot -Filter @{Snapshot = ''} |
select Name
Like Show 0 Likes(0)

Actions
2. Re: Listing all snapshots per vm using get-view

Marco_2_G May 23, 2018 5:39 AM (in response to LucD)

Hi LucD

That gives me a list of all the vms that have snapshots.

I need to have a list of all the snapshots for each of the vms returned.

Regards,

Marco
Like Show 0 Likes(0)

Actions
3. Re: Listing all snapshots per vm using get-view

LucD May 23, 2018 6:20 AM (in response to Marco_2_G)

Ok, that requires a few more lines of code.
Try like this

function Get-SnapChild{
   param(
[VMware.Vim.VirtualMachineSnapshotTree]$Snapshot
   )

   process{
   $snapshot.Name
   if($Snapshot.ChildSnapshotList.Count -gt 0){
   $Snapshot.ChildSnapshotList | %{
   Get-SnapChild -Snapshot $_
}
}
}
}

foreach($vm in Get-View -ViewType VirtualMachine -Property Name,Snapshot -Filter @{'Snapshot' = ''}){
   $vm.Snapshot.RootSnapshotList | %{
   Get-SnapChild -Snapshot $_ | Select @{N='VM';E={$vm.name}},@{N='Snapshot';E={$_}}
}
}

1 person found this helpful
Like Show 1 Likes(1)

Actions
4. Re: Listing all snapshots per vm using get-view

Marco_2_G May 23, 2018 6:26 AM (in response to LucD)

Thank you, this works. I have no idea why it works but that's more due to my being a novice when it comes to coding and powershell in particular .

I'll be staring at this code in total incomprehension some more now.
Like Show 0 Likes(0)

Actions
5. Re: Listing all snapshots per vm using get-view

LucD May 23, 2018 6:35 AM (in response to Marco_2_G)
Lol!

To minimise the staring, some annotations:
To filter the VMs that have a snapshot, the Get-View Filter parameter checks if the Snapshot property is $null or not. This translates to checking for an empty string, which is Get-View/RegEx speak for -not $null
On a VM there is the RootSnapShotList which points to the snapshot that make up the roots of all snapshot trees. For each root snapshot, we recursively traverse the snapshot tree via the Get-SnapChild function
In the Get-SnapChild function we avoid the issue with a Foreach loop that runs once, even with an empty array, by testing for the number of entries in the ChildSnapshotList array
when a child snapshot has children, the function calls itself again. This is the recursive part
Like Show 0 Likes(0)

Actions
6. Re: Listing all snapshots per vm using get-view

Marco_2_G May 23, 2018 6:38 AM (in response to LucD)

I may now understand your code. If you have the time I'd live for you to verify this:

Am I correct in assuming that the process block is more good coding style than strictly necessary?

Anyway as far as I can tell, you take the rootsnapshotlist which has an attribute childsnapshotlist (THIS is exactly the piece of linking information I was unable to find so far) and if it has more than 0 entries you traverse through those snapshots by calling your function inside itself.

The function then returns everything it has found through the first line after process{ and all you have to do is clean the output up a bit through the select statement.

Am I understanding this somewhat correctly?

And thanks again for the help.
Like Show 0 Likes(0)

Actions
7. Re: Listing all snapshots per vm using get-view

Marco_2_G May 23, 2018 6:40 AM (in response to Marco_2_G)

Oh, you were faster than I was

Thanks, I believe I've got it!

You're an invaluable source of info... but I'm sure I'm not telling you anything new.
Like Show 0 Likes(0)

Actions
8. Re: Listing all snapshots per vm using get-view

LucD May 23, 2018 6:44 AM (in response to Marco_2_G)

Correct, the function could be done without the Process block
Strictly speaking Begin-Process-End blocks are when objects are passed over the pipeline to the function.

The function just returns the names of all the snapshots it finds.
The Select is to combine that info with the VM name.
Like Show 0 Likes(0)

Actions
9. Re:Listing all snapshots per vm using get-view

Sudarshan_Bharti Oct 27, 2018 4:20 PM (in response to Marco_2_G)

Get-View -ViewType VirtualMachine -Filter @{"snapshot" = ""} -Property Name | % {Get-VM -id $_.MoRef | Get-Snapshot}
Like Show 0 Likes(0)

Actions
10. Re: Listing all snapshots per vm using get-view

ndnguyen May 20, 2019 8:46 AM (in response to LucD)

How would i add Date created, created by and description?
Like Show 0 Likes(0)

Actions
11. Re: Listing all snapshots per vm using get-view

LucD May 20, 2019 8:59 AM (in response to ndnguyen)

Like this.
For the user that created the snapshot, you will have to search the events.
See for example Re: snapshot who created it

function Get-SnapChild
{
   param(
   [VMware.Vim.VirtualMachineSnapshotTree]$Snapshot
   )

   process
   {
   $snapshot | Select Name, Description, CreateTime
   if ($Snapshot.ChildSnapshotList.Count -gt 0)
   {
   $Snapshot.ChildSnapshotList | % {
   Get-SnapChild -Snapshot $_
   }
   }
   }
}

foreach ($vm in Get-View -ViewType VirtualMachine -Property Name, Snapshot -Filter @{'Snapshot' = '' })
{
   $vm.Snapshot.RootSnapshotList | % {
   Get-SnapChild -Snapshot $_ |
Select @{N = 'VM'; E = { $vm.name } },
   @{N = 'Snapshot'; E = { $_.Name } },
   @{N = 'Description'; E = { $_.Description } },
   @{N = 'CReated'; E = { $_.CreateTime } }
   }
}

1 person found this helpful
Like Show 1 Likes(1)

Actions
12. Re: Listing all snapshots per vm using get-view

ndnguyen May 20, 2019 9:23 AM (in response to LucD)

Thank you very much for the quick responce. Much appriciated.
Like Show 0 Likes(0)

Actions