vCenter Server Virtual Appliance (vCSA) is still very rare in a production environment. This might change with the current enhancements to the scalability made in vSphere 5.5. The maximum supported numbers of the embedded database have been lifted to 100 ESXi hosts and 3000 virtual machines. From now on, there are only a few imitations remaining. I do not think that many environments hit the scale limit, so the only remaining limitations are Windows-related limitations.
Here are the limitations from VMware vCenter Server Appliance 5.5
The embedded Database supports up to 100 hosts and 3000 virtual machines. This only applies to the internal Database. The external Database requires Oracle and supports up to 1000 hosts and 10000 virtual machines.
As linked mode is based on Microsoft Active Directory Application Mode (ADAM) to synchronize data across multiple vCenter Server systems it is not supported in vCenter Server Appliance.
vCenter Server Heartbeat
VMware vCenter Server Heartbeat is a Windows Application and can only protect a Microsoft SQL Server database.
Security Support Provider Interface (SSPI)
The Security Support Provider Interface (a part of SSO) is a Microsoft Windows API used to perform authentication against NTLM or Kerberos.
VMware Update Manager
The VMware Update Manager is only available for Windows. You can't install it inside the vCSA but you can install it on an external Windows System and use it with your vCSA.
The View Composer is only available for Windows. But it is no longer required to install it on the same system as the vCenter Server. A standalone View Composer installation works with the Linux-based vCenter Server Appliance.
As I am sure you are aware that the actual maximum supported hosts and VMs of the vCSA 5.5 is 1,000 hosts and 10,000 VM just like the Windows version of vCenter. The limits mentioned in this article is only applicable when the vCenter Server Appliance 5.5 is using the embedded vPostgres Database.
After getting in an argument with couple of customers who misinterpreted my original blog post: http://www.virtualizationteam.com/server-virtualization/vcenter-server-appliance-5-5-limitations.html and many others including yours where we quoted these numbers without taking the time to mention it only apply when using the embedded database is being used, customers are getting confused. I have updated mine and I have been requesting other bloggers to fix them if possible to make it easier for the rest of us in the field as customers use such blog posts when arguing about the validity of their information.
Absolutely true. It was such a great enhancement that i just forgot the Database paragraph in the limitation listing like in my older VCSA 5.1 limitations post.
I've update my post to make it more clear.
Thanks for drawing attention.
Not a problem, & I did the same mistake at first till I noticed how much confusion my article has caused then end up fixing them as well :).