VMware vCenter Server Appliance 5.5 has been gaining huge attraction lately, especially with many of the major limitations affecting the vCenter Appliance in previous verions have been lifted. This is including the limitation where it was only supposed to support 5 hosts and 50 VMs when using the embedded database. In fact the all shiny new VMware vCSA 5.5 support up to 100 hosts and 3000 VMs using the embedded database, which seems to be able to deliver up to the scale required by most customers.

Note: It seems a misleading assumption has been going around that 100 hosts and 3,000 VMs is the maximum supported configuration by VMware vCSA 5.5, where is that is absolutely not true. This limit only apply when using the embedded  built-in vPostgres where it actually can support up to the vCenter maximums of 1,000 hosts and 10,000 VMs when connected to an external Oracle Database. This is clearly documented on page 7 of vSphere 5.5 Maximums guide and a copy of that table is shown below. I believe this misleading belief has spread as many bloggers has mentioned the 100 hosts and 3,000 VMs limit while failing to point out it is not the actual limit of the appliance, but it only apply when using the embedded database. 

I have actually been using VMware vCenter Server Appliance 5.5 for most of my labs and at various customers as it deliver what they needs, as it can be deployed in fraction of the time and save them from having to build Windows and DB servers, not to mention its easier to maintain and manage. That has been said, the VMware vCenter Appliance 5.5 is still not for everyone, & still has some limitations that you need to ensure they are not of a concern in your environment. To help you out finding out if the VMware vCenter Server Appliance is right for you, I have documented below the main vCSA 5.5 limitation for you to use as a check list before deciding to go with the VMware vCenter Server Appliance:

VMware vCenter Server Appliance 5.5 limitations:

• vCenter Linked Mode is not supported
• vCenter Heartbeat is not supported
• Some VMware/Third Party Plugins might not support vCSA. Check with your desired plugin vendors if they support the vCenter Appliance.
• Installing update Manager on the vCenter Appliance is not supported, but you can still set it up on a separate Windows VM.
• If using the embedded database you will be limited to 100 hosts and 3000 VMs, but you always can utilize an Oracle Database to be able to scale to the vCenter Maximums of 1000 hosts and 10,000 VMs.
• MS SQL Database is currently not supported by the vCenter Server Appliance, where you can either use the built-in vPostgres (Support up to 100 hosts and 3000VMs) or you will need to use Oracle Database to scale to 1000 hosts and 10,000 VMs. If you are planning to go beyond 100 hosts and 3000VMs and Oracle database is not an option or your cup of tea then you will have to stick with the Windows version of vCenter for now.
• It does not support the Security Support Provider Interface (SSPI),  which is a part of SSO, and  is a Microsoft Windows API used to perform authentication against NTLM or Kerberos.
• VMware View Composer can not be installed on the vCenter appliance, but it is no longer required to install it on the same machine as vCenter and it can be installed on a different machine and then it will support vCSA.

Hope this help you identify if the vCenter Appliance 5.5 is right for you, and if you are ready to deploy the vCenter Server Appliance 5.5, then my following post can help you though setting it up: vCenter Server Appliance 5.5 Installation Step by Step