Cross vMotion – Page 5

Are Affinity/Anti-Affinity rules preserved during Cross vCenter vMotion (xVC-vMotion)?

04.02.2015 by William Lam // Leave a Comment

Among other things, vSphere Affinity/Anti-Affinity rules are indeed preserved with a Virtual Machine during a Cross vCenter vMotion (xVC-vMotion) which is a new vMotion capability in vSphere 6.0. If you wish to learn more about this awesome new feature be sure to read about it here and here.

There were a couple of people asking about the details on how this actually worked so I figured I would set this up in my lab and provide some additional information. In my environment I have two vCenter Server 6.0 joined to a single Platform Services Controller (same SSO Domain) which provides me with the Enhanced Linked Mode capability which is one of the requirements for a regular xVC-vMotion as it needs to be visible in the vSphere Web Client. You can also do an ExVC-vMotion, which does not require the vCenter Servers to be part of the same SSO Domain, you can find more details in this blog post here.

I initially had 3 Virtual Machines called: Web1, Web2 and Web3 which ran in my "PA-VSAN-Cluster" which is located in my first vCenter Server. I then create an Anti-Affinity rule called "Web-Rule" that ensures all three VMs are running on separate ESXi hosts. I then manually perform xVC-vMotion (remember automated DRS migration is on a vSphere Cluster boundry and will not vMotion outside of a vSphere Cluster or vCenter Server) each VM to my secondary vCenter Server to my "SB-VSAN-Cluster"

Once the VM has successfully relocated to the destination site, the Affinity/Anti-Affinity rules are then migrated over. You might be wondering why the Affinity/Anti-Affinity rule could not be created in advance and the reason is because it needs the actual VM object to be available to associate the the rules to. Once all three VMs have been migrated over, you will see that the old Affinity/Anti-Affinity rule no longer exists in the source vCenter Server and now lives in destination vCenter Server as seen in the screenshot below. Simple and elegant!

Duplicate MAC Address concerns with xVC-vMotion in vSphere 6.0

03.05.2015 by William Lam // 4 Comments

In vSphere 6.0, the mobility options for a Virtual Machine is truly limitless. This has all been possible with a new set of vMotion capabilities introduced in vSphere 6.0 which you can learn more about them here and here. In the past, one area of concern when migrating a VM from one vCenter Server to another is the possibility that a migrated VM's MAC Address might be re-provisioned by the source vCenter Server resulting in a MAC Address conflict. In fact, this is actually a topic I have covered before in my considerations when migrating VMs between vCenter Servers article. I highly encourage you check out that article before proceeding further as it provides some additional and necessary context.

When looking to leverage the new Cross vCenter Server vMotion (xVC-vMotion) capability in vSphere 6.0, are MAC Address conflicts still a concern? To answer that question, lets take a look at an example. Below I have a diagram depicting two different vSphere 6.0 deployments. The first is comprised of three vCenter Servers who are joined to the same SSO Domain called vghetto.local and VM1 is currently being managed by VC1. The second is a single vCenter Server connected to a completely different SSO Domain called vmware.local. I will also assume we are being a good VI Admin and we have deployed each vCenter Server using a unique ID (more details here on why having different VC ID matters).

Lets say we now migrate VM1 from VC1 to VC2. In previous releases of vSphere, this potentially could lead to VC1 re-provisioning the MAC Address that VM1 was associated with because that MAC Address was no longer being managed by VC1 and from its point of view, it is now available. Though this type of a scenario is probably rare in most customer environments, in a high churn continuous integration or continuous delivery environment, this can be a real issue. So has anything been improved in vSphere 6.0? The answer is yes, of course 🙂

In vSphere 6.0, vCenter Server now maintains a VM MAC Address Blacklist which upon a successful xVC-vMotion will update this blacklist with the MAC Addresses associated with the migrated VM. This ensures that the source vCenter Server will not re-provisioned these MAC Addresses to newly created VMs and these MAC Addresses are basically "blacklisted" from being used again as shown in the diagram below.

If we decide to migrate VM1 from VC2 back to VC1, the blacklist is automatically updated and "blacklisted" MAC Addresses will be removed. If we decide to migrate VM1 to a completely different vCenter Server which is not part of the same SSO Domain, ~~then the MAC Address could potentially be re-used~~, but it will depend on your environment if VC4 is on a completely different L2 segment, then a MAC Address conflict would not occur.

As of right now, there is no automatic way of reclaiming blacklisted MAC Addresses, it is a manual process that must be initiated through a private vSphere API. I am hoping we will be able to get this documented in an official VMware KB, so that in case this is required, you can easily follow the simple steps to execute the necessary APIs. Automatic reclamation is being looked at by Engineering and hopefully we will see this in a future patch/update in vSphere. Overall, this should should not really be a concern given that vCenter Server can uniquely generate about 65,000 unique MAC Addresses and you would have to perform quite a few xVC-vMotions before ever needing to reclaim from the blacklist.

One thing to be aware of when performing xVC-vMotion or ExVC-vMotion is that there are currently no pre-flight checks for MAC Address conflicts at the destination vCenter Server (something Engineering is looking update in a future patch/update release). Having said that, there are two additional measures you can implement in you environment to prevent MAC Address conflicts:

Create vCenter Server alarm which can detect and notify you of a duplicate MAC Address in you environment (also applicable to vSphere 5.5)
Pro-actively check to see if the existing MAC Addresses of your VM is currently in use prior to performing a xVC-vMotion, this is especially useful when performing ExVC-vMotion.

To help with with number 2, I have created a simple PowerCLI script called check-vm-mac-conflict.ps1 which accepts both your source and destination vCenter Server as well as the name of the VM in the source VC to be migrated. It will check the VM's MAC Addresses in the destination VC and ensure that there are no conflicts. If there is a conflict, it will output the name of the destination VM and the MAC Address that is in conflict as seen in the screenshot below.

Hopefully with these additional measures, you can easily prevent MAC Address conflicts when performing xVC-vMotions in your vSphere environment which can be a pain to troubleshoot.

Did you know of an additional cool vMotion capability in vSphere 6.0?

02.19.2015 by William Lam // 59 Comments

There was an excellent blog post from Duncan a couple of weeks back going over the new vMotion capabilities in vSphere 6.0 which includes: Cross vSwitch vMotion, Cross vCenter vMotion (xVC-vMotion) and Long Distance vMotion (LD-vMotion). If you have not checked out his article, I highly recommend you give it a read before proceeding further. After reading through Duncan's article, I noticed he had missed out on one additional vMotion capability which might not be obvious as the option is no where to be found in the vSphere Web Client UI. In fact, I was only aware of this additional capability after hearing about it from Engineering during the development of vSphere 6.

The additional vMotion capability actually extends the Cross vCenter Server vMotion (xVC-vMotion) workflow which allows an administrator to live migrate a running virtual machine between two vCenter Servers that are part of the same SSO Domain. By virtue of being in the same SSO Domain using the new Enhanced Linked Mode feature, both vCenter Servers will be visible in the vSphere Web Client and will be available to be selected either as a source or destination for a vMotion operation.

This extended Cross vCenter Server vMotion capability (unofficially I am calling it ExVC-vMotion) allows an administrator to live migrate a running virtual machine between two vCenter Servers which are NOT part of the same SSO Domain. How cool is that!? In my opinion, this is actually a pretty big deal because I think it truly removes any boundaries for a vSphere virtual machine and will open up an entire new class of mobility use cases that were never thought possible before. This will definitely make it interesting for customers who wish to migrate workloads from their on-premises datacenter into a completely different vSphere environment or even one that is hosted by a service provider or maybe even vCloud Air?

The ExVC-vMotion operation is currently only available today using the vSphere API, not because it is a private API but because there is no UI wizard for this operation. The reason the current xVC-vMotion is so seamless today is that both your source and destination vCenter Server is visible by being part of the same SSO Domain. If you have two completely different vCenter Servers which are not joined to the same SSO Domain or have completely different SSO Domains, then you will need to use the vSphere API to perform this operation.

All vMotion operations including vMotion without shared storage uses the vSphere API RelocateVM_Task() method. In vSphere 6.0, the method has been enhanced to accept a new property called ServiceLocator which provides a service endpoint to a vCenter Server where a VM can be migrated to. One important thing to note is that if you wish to migrate a VM between two vCenter Servers located in the same SSO Domain, there is an sslThumbprint property that is not required to be set. However, if the two vCenter Servers are NOT part of the same SSO Domain, then you need to set that property. In addition, if the VM is migrated to a different vCenter Server, additional properties such as the ESXi host, vSphere Cluster/Resource Pool and Datastore must be specified as part of the migration spec.

UPDATE (05/25/16) - I have re-factored and simplified my xVC-vMotion script which supports additional capabilities. Please have a look at the blog post here for more details.

To demonstrate this awesome ExVC-vMotion operation, I have created a simple PowerCLI script called run-cool-ExVC-vMotion.ps1 which accepts 12 command-line parameters which are described in more detail below:

Variable	Description
sourceVC	The hostname or IP Address of the source vCenter Server
sourceVCUsername	The username to connect to source vCenter Server
sourceVCPassword	The password to connect to source vCenter Server
destVC	The hostname or IP Address of the destination vCenter Server
destVCUsername	The username to connect to the destination vCenter Server
destVCPassword	The password to connect to the destination vCenter Server
destVCThumbprint	The SSL Thumbprint (SHA1) of the destination vCenter Server (can be retrieved using either this or this)
datastorename	The destination vSphere Datastore where the VM will be migrated to
clustername	The destination vSphere Cluster where the VM will be migrated to
vmhostname	The destination vSphere ESXi host where the VM will be migrated to
vmnetworkname	The destination vSphere VM Portgroup where the VM will be migrated to
vmname	The name of the source VM to be migrated

In my lab environment, I have configured two vCenter Server's which are part of two different SSO Domains as seen in the screenshot below:

I have tiny Linux VM (vMA) that I am using which I will be migrating from vcenter60-4 to vcenter60-5 which has a completely different datastore and VM portgroup (if you have stretched/extended L2, then the VM would stay online during this migration). I then execute the script using the following parameters based on my own environment and we can see the migration is kicking off:

.\run-cool-ExVC-vMotion.ps1 vcenter60-4.primp-industries.com *protected email* VMware1! vcenter60-5.primp-industries.com *protected email* VMware1! 82:D0:CF:B5:CC:EA:FE:AE:03:BE:E9:4B:AC:A2:B0:AB:2F:E3:87:49 vesxi60-8-local-storage NY-Cluster vesxi60-8.primp-industries.com NY-VM-Network vMA

One the migration has completed, if we now take a look at our vSphere Web Client, we can see the VM has now been migrated to the other vCenter Server.

I really hope to see the vSphere Web Client get enhanced to support this cool vMotion capability, but in the mean time you can easily perform this operation using the above PowerCLI script or any other scripting/programming language calling into the vSphere API. Set your VM free and let it migrate where your heart desires 🙂