What Does The Platform Services Controller Do

The Platform Services Controller (PSC) is a new infrastructure component that was first introduced in vSphere 6.0 that provides common services such every bit Unmarried Sign-On, Licensing and Certificate Management capabilities for vCenter Server and other VMware-based products. A PSC tin be deployed on the same arrangement as the vCenter Server referred to as an Embedded deployment or outside of the vCenter Server which is known as an External PSC deployment. The primary utilise instance for having an External PSC is to be able to take reward of the new Enhanced Linked Way (ELM) characteristic which provides customers with a unmarried pane of drinking glass for managing all of their vCenter Servers from inside the vSphere Web Client.

When customers outset to plan and blueprint their vSphere 6.0 compages, a topic that is usually brought upward for discussion is whether or not they should be load balancing a pair (upwards to four) of their PSC's? The idea behind using a load balancer is to provider higher levels of availability for their PSC infrastructure, however it does come as an additional toll both from an Opex and Capex standpoint. More importantly, given the added complexity, does it actually provide you with what y'all recollect information technology does?

A couple of things that stood out to me when I look at the process (VMware KB 2113315) of setting up a load balancer (VMware NSX, F5 Big-IP, & Citrix NetScalar) for your PSC:

The load balancer is not actually "load balancing" the incoming requests and spreading the load across the different backend PSC nodes
Although all PSCs behind the load balancer is in an Active/Active configuration (multi-master replication), the load balancer itself has been configured to affinitzed to just a single PSC node

When talking to customers, they are generally surprised when I mention the above observations. When replication is setup between one or more PSC nodes, all nodes are operating in an Active/Active configuration and any one of the PSC nodes can service incoming requests. However, in a load balanced configuration, a single PSC node is really "affinitized" to the load balancer which will be used to provide services to the registered vCenter Servers. From the vCenter Server's point of view, simply a unmarried PSC is really agile in servicing the requests fifty-fifty though all PSCs nodes are technically in an Agile/Active state. If you wait at the implementation guides for the three supported load balancers (links higher up), y'all will run into that this bogus "Agile/Passive" behavior is actually achieved by specifying a college weight/priority on the master or preferred PSC node.

So what exactly does load balancing the PSC really buy you? Well, information technology does provide y'all with a higher levels of availability for your PSC infrastructure, just it does this by simply failing over to 1 of the other available PSC nodes when the master/preferred PSC node is no longer available or responding. Prior to vSphere 6.0 Update ane, this was the only other option to provide higher availability to your PSC infrastructure exterior of using vSphere HA and SMP-FT. If you ask me, this is a pretty complex and potentially plush solution just to get a basic automatic node failover without whatsoever of the real benefits of setting up a load balancer in the starting time place.

In vSphere 6.0 Update 1, we introduced a new capability that allows u.s. to repoint an existing vCenter Server to another PSC node every bit long equally it is part of the same SSO Domain. What is really interesting well-nigh this characteristic is that y'all can actually become a similar behavior to what y'all would have gotten with load balancing your PSC minus the added complexity and price of actually setting upwardly the load balancer and the associated configurations on the PSC.

load-balancing-psc
In the diagram above, instead of using a load balancer equally shown in the left, the culling solution that is shown to the correct is to manually "failover" or repoint to the other bachelor and Agile PSC nodes when the master/preferred is no longer responding. With this solution, yous are notwithstanding deploying the same number of PSC'south and setting upward replication between the PSC nodes, only instead of relying on the load balancer to perform the failover for you automatically, you would exist performing this operation yourself past using the new repoint functionality. The biggest benefit here is that you get the aforementioned outcome as the load balanced configure without the added complexity of setting up and managing a single or multiple load balancers which in my opinion is huge cost. At the end of the day, both solutions are fully supported past VMware and information technology is of import to empathize what capabilities are provided with using a load balancer and whether it makes sense for your organization to take on this complication based on your SLAs.

The only down side to this solution is that when a failure occurs with the primary/preferred PSC, a manual intervention is required to repoint to i of the available Active PSC nodes. Would information technology non exist cool if this was automatic? ... 🙂

Well, I am glad you asked as this is exactly what I had idea about. Below is a sneak peak at a log snippet for a script that I had prototyped for the VCSA which automatically runs a scheduled job to periodically bank check the health of the primary/preferred PSC node. When it detects a failure, information technology will retry N-number of times and when concludes that the node has failed, it will automatically initiate a failover to the available Active PSC node. In addition, if you accept an SMTP server configured on your vCenter Server, it can as well send out an e-mail notification nigh the failover. Stay tune for a future blog mail service for more details on the script which can exist constitute hither.

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