We are undertaking an upgrade in network infrastructure from 1Gb links to a dedicated 10Gb network for storage. The new network has separate pnics/vswitch/vmkernel, along with a separate VLAN, but it accesses the exact same storage volumes (NFS on Netapp) as the 1Gb links. It appears that when connecting to the same datastore from 2 different vmkernels, vCenter treats them as different, and will not allow vMotion between them. We will need to have both 1Gb and 10Gb storage connections available until the migration is complete in case a vMotion is needed.
Testing with some non-production equipment, it appears that I have 3 options for migrating the VMs:
-Storage vMotion: no downtime, but slow for larger VMs. Destination storage is same as source (just accessed through a different vmkernel), but it appears to work OK.
-Cold migrations: downtime, also slow for larger VMs. If VM is already off, remove/rereg is better solution
-Remove from inventory/re-register VM: downtime, but much quicker than cold migration
While our environment is not huge (about 200VMs over 7 hosts), I would like to do this as efficiently as possible. Has anyone gone through this sort of change before, and is there any other way to do this? We are relatively new to vSphere 4 and have not played too much with PowerCLI, but if there is something there that will make my life easy, I will definitely check it out.
Search the Communities for the ghetto script repository. There is a script that will do a pause, unregister, register, unpause. I'm not at a computer so you will need to look for it.
I am looking at the exact same scenario you ran into. Which option did you end up using? We're on vSphere 5.1 now, so I'm wondering if they are implemented anything to ease this process.
We ended up with a combination of Storage VMotions or unregister/re-register for our VMs, depending on whether we could get a maintenance window for them or not. It is going back in time a bit, but I do remember a few caveats to the whole process. This was all in v4.1 so I am not sure if there is anything new that makes it easier in v5.1.
A few things that I remember that you should be aware of:
-You will briefly need double the space available in your datastore that the VM uses during the copy, as the source and destination datastore for the Storage VMotion is the same physical place on the storage.
-Depending on your storage platform (Netapp for us), you may need to keep an eye on things like snapshot space taken, etc so you don't run out of space in the datastore, as there is a lot of change in the datastore through this.
-If you unregister a VM, I believe you will lose all the historical VM performance data from vCenter. This was not a big deal to us, but that might be different for you.
Hope this helps you out a bit,