Wednesday, October 31, 2012

Aligning VMs via Netapp VSC 4.1

With Netapp's release of VSC 4.1 for VMware comes support for online alignment of VMs residing on NFS datastores.  We aligned 99% of our VMs 1-2 years ago the only way possible back then, by powering them down and running mbralign - which meant large VMs soucle be down for hours.

So we were excited to see the Scan Manager go through the datastores we chose and classify our VMs

As either Aligned (actually or functionally) or Misaligned (online or offline)

But when we went to align the NFS based VMs we received the error:

Selecting Yes, you are given the choice to Use and existing datastore or create a new one

We selected Create new but got this error

The iscsi devices were enabled on the controller (according to the command line)
dr-na-01> iscsi interface enable -a
Interface e0a already enabled
Interface e0b already enabled
Interface e0c already enabled
Interface e0d already enabled

But to make them VSC enabled we had to go Provisioning and Cloning -> select the controller -> Resources  and shift all the resources to the right

Once we did all this, VSC was able to create the iSCSI VMFS datastore and migrate the VM from misaligned on NFS to "functionally aligned" on the iSCSI datastore.

However we don't run iSCSI (or FC) datastores - we need VSC to support creating optimized (functionally aligned) NFS datastores.

According to Netapp support: "there are quite a few Gotcha’s when it comes to NFS alignment, so we have not yet made it a standard feature of VSC online migration"

Well, maybe in VSC 4.2?


Anonymous said...


NetApp Employee here.

VSC 4.1 has all the bits to do online IO alignment with NFS datastores as the target but it needs a supporting functionality which was made available in ONTAP 8.1.1. The functionality has to be activated after an approval from NetApp support since they want to be aware of who is using it. The approval process can be initiated by your account team.

I believe that the process will be waived in the future.


Satinder Sharma (@storarch)

Anonymous said...

Just wanted to update that non-disruptive IO alignment for NFS datastores is now GA with VSC 4.2

Unknown said...

The online-alignment from NetApp means, that you move a misaligned VM to a new purposely misaligned datastore which reversed the offset of the VMDKs?

Is it right?