Get-view, viewtypes, filter, Get-VIObjectbyVIView

From time to time i check my blog to see how people are getting to my blog 😉 Today i thought that if so many of you are trying to find this information although for some reason it is not in that post to which you are being redirected, i will create a new post about it. So that you will not be disappointed that the information is not there.
So few things about get-view. I think that VMware offers a GREAT documentation so why not take their explanation 😉

The vSphere PowerCLI list of cmdlets includes the Get-View and Get-VIObjectByVIView cmdlets, which enable access to vSphere PowerCLI views from .NET.Using the vSphere PowerCLI views cmdlets for low-level VMware vSphere management requires some knowledge of both PowerShell scripting and the VMware vSphere APIs.

In few words… While installing powercli you receive a set(a great set 😉 ) of cmdlets. You can get info about vms,datastores,clusters etc, etc… You can run verb cmdlets like set/new/invoke/move/restart/start/stop etc, etc.. well you can see it yourself executing ‘get-vicommand’ how many of those there are 😉 But in case that’s not enough you can access vsphere objects using views. You will discover that they provide even more options than cmdlets. Some things can’t be done using powercli cmdlets, and they need to be executed using views and their methods. Views also provide access to specific managers like license manager, alarm manager etc…

Get-View

I think that the most common mistake in my opinion is to get the view from get-vm. Well i was doing it myself too 😉

So then i could have an array with all views.
Now this not necessary to pass get-vm objects via pipeline to get-view. It works ok, but get-view can get virtual machines on it’s own.

There 😉 1 command. You can ask now how did i know that there was a viewtype like this. For example :
get-vm -name testvm
takes 1 second and 994 milliseconds
where
get-view -viewtype virtualmachine -filter @{‘name’=’testvm’}
takes 0 second and 455 milliseconds
Those measurements were taken on a small scale infra ~1000 vms.

Whereas get-vm will provide us an object to use with other cmdlets, no methods like above at all. One more thing about this last sentence. Since PowerCLI 4.1 you can access those setting via get-vm as well. Extensiondata object was introduced. And if you need to access properties from views, you do:

which will act in the same way as

So now if you need to take some property value from the view, and you have already some object from get-vm there is no need to pipe it to get-view. Instead you can access that property directly like:

That will be the same as with using get-view approach:

Ok so Greg… now you are confusing ME !!!!!!!!!!!!!!!!!!!!!
– I know , i am sorry ! 😉
For reporting purposes i would choose approach with get-view only, due to performance boost. It executes way faster than having data from get-vm checked and filtered.

That would take 658 milliseconds on small scale infra to complete.

That would take 1 minute and 58 seconds to complete. The result is the same, we have queried for vms that run without vmware tools. The difference is in time it took to present this data.
Get-view by default will also include templates when asked with virtualmachine viewtype. You can exclude that using filter

Now the number of vms returned should be equal to number of vms returned from get-vm.

viewtype

Viewtype from get-view supports those views:
ComputeResource, ClusterComputeResource, Datacenter, Datastore, Network, DistributedVirtualPortgroup, DistributedVirtualSwitch, Folder, HostSystem, ResourcePool, VirtualApp, VirtualMachine, VmwareDistributedVirtualSwitch

So the type can be read from moref, which is managed object reference object. What also should work (but at this time it is not working for me ;( ), you can try to run ‘get-view -viewtype xyz ‘ , it will force get-view to tell you what views does he support. For some reason it is not working for me when i am using powercli 5.x . It returned those values in previous versions though 😉

So, in order to get different views than virtualmachine:
get-datastore but using view: get-view -viewtype datastore
And so on and on… I hope that by now you will still remember about our Extensiondata 😉 (get-datastore “ds01”).Exensiondata

filters

About filters for get-view.
Like in example: get-vm -name t*
would return all vms that start on letter t, we can do the same with get-view using filters

Filter is descirbed in manual for vsphere manual documentation

The filter parameter is a HashTable object containing one or more pairs of filter criteria. Each of the criteria consists of a property path and a value that represents a regular expression pattern used to match the property.

Note that all filter parameters must mach.You can use regex inside filter. ‘name’=’^t’ would indicate that FIRST letter should be t.
Ok, lets filter it more. I want views from vms that start on letter t, and they are powered on

You can check what’s the actual powerstate from this property, so we can use it in our filter

Ok but let’s say that you are looking for vms that start on letter t and L . So how are we supposed to put t AND L in the same name filter?
Since you are using regex there, you can apply OR

One more question could be :
Ok, i want to use my get-view on some specific location like clusterA:
get-view -viewtype virtualmachine -SearchRoot (get-cluster -name ‘clusterA’).id
where SearchRoot is :”Specify a starting point for the search (in the context of the inventory).” taken from vsphere documentation
😉 and so on and on. When you want to attach your query to some location use the -SearchRoot switch

One other thing. So let’s say that you are in middle of doing “stuff” on objects from get-view. And for some reason you want them to interact with powercli cmdlets. If i would take now my view object $myvm=get-view -viewtype virtualmachine -filter @{‘name’=’testvm’} and would like to start it or stop it using powercli cmdlets like start-vm, stop-vm, it will not work. It works only with virtual machine objects returned from get-vm, not from views. But VMware gave us additional cmdlet to help us out in those situations.

There 😉 It works now ! So how get-viobjectbyviview has helped us ?

Converts a vSphere View object to a VIObject using the object ID provided by the MoRef parameter. If the View object is a ServiceInstance, you cannot convert it to a VIObject.

From the moment that object leaves get-viobjectbyviview it will become the same virtualmachine object as it would come from get-vm testvm. And we can now use with other powercli cmdlets.
When can i apply this command ? Ok , i will give now 1 example. You probably know that running get-snapshot will take a while in bigger infra right ?

We can still query for vms with snapshots using get-view with filter:

This will output view for vms that have snapshot. That’s cool, but what’s next if you can’t pipe this output to remove-snapshot cmdlet. Get-VIObjectbyVIView ! Bingo 😉

You can then interact with those objects using powercli cmdlets.
One more thing, the powercli version 5.0.1 build 581491 has problem with running get-viobjectbyviview . Either update your powercli version or make a tiny fix 😉

In order to fix that i had to pass manually moref to get-viobjectbyviview.

Summary

I hope this post explains a little bit of differences between get-vm and get-view. If you have any questions please post a comment and i will update the post then.
Another post that i wrote recently that explains it as well http://grzegorzkulikowski.info/2014/02/02/find-cpu-hogging-vms-using-powercli/