vCenter

why MS SQL server  is required for vcenter installation ?

You need a database to hold the vCenter Server information. It can be SQL/Oracle. By default, a SQL express installation happens if you do not wish to install a full blown SQL Server - it will have maximum limitations but work for smaller infrastructure.

Exact Wording from the documentation:

vCenter Server and vCenter Update Manager require databases to store and organize server data.

Each vCenter Server instance must have its own database. vCenter Server instances cannot share the same database schema. Multiple vCenter Server databases can reside on the same database server, or they can be separated across multiple database servers. For Oracle databases, which have the concept of schema objects, you can run multiple vCenter Server instances in a single database server if you have a different schema owner for each vCenter Server instance, or use a dedicated Oracle database server for each vCenter Server instance.

You do not need to install a new database server for the vCenter Server installation to work. During installation, you can point the vCenter Server system to any existing supported database. vCenter Server supports IBM DB2, Oracle, and Microsoft SQL Server databases. vCenter Update Manager supports Oracle and Microsoft SQL Server databases. For a list of supported database server versions, see the vSphere Compatibility Matrixes athttp://www.vmware.com/pdf/vsphere4/r40/vsp_compatibility_matrix.pdf on the VMware vSphere documentation Web site.

Plan accordingly if you plan on having more than 5 hosts you are going to go want to go with full blown SQL rather than the free SQL express version. This assumes of course you are picking SQL for your DB.

You can also just deploy the vCenter appliance it comes with its own built in DB.

Also keep in mind if you choose to host it on a Windows box with a DB back end you will not be able to migrate that over to the virtual vCenter appliance in the future and vice versa.

We found ourselves in that boat, we are running vCenter with SQL and are tired of having to manage a Windows server just for vCenter, so we thought we would migrate to the virtual appliance. Nope not possible. Not a big deal but good knowledge to have PRIOR to deciding how to build your vCenter.

Thanks for the reply :smileyhappy: