The install guide says:
The system that you use for your vCenter Server installation must belong to a domain rather than a
workgroup. If assigned to a workgroup, the vCenter Server system is not able to discover all domains and
systems available on the network when using such features as vCenter Guided Consolidation Service....
Is it possible or advisable to install vcenter 4 without AD? The environment is 3 esxi servers with vsphere enterprise plus, vcenter and lab manager (4). This is a new installation with no production machines to virtualise. Users currently authenticate via a Sun LDAP server.
If I use AD it will have an domain controller on the virtual environment
You can install vCenter server without AD. But you will not able to make use of certain features like GCS, linked mode VC etc. But if you are not planning to use all these features, you can very well go for installation on a machine in workgroup.
Hope this helps