I would do either thin or thick lazy zeroed.  Both will take up the same amount of data on the Compellent.  The main decision is where do you want to manage your storage?  If you do thin on thin you have to make sure you do not over provision in both places.  If you do thick lazy zeroed then you can only over provisioning on one side. Saying that  I always do thin on thin.  Reclaiming space at the VM level is not officially supported right now, but maybe one day. In a virtualized environment, always do simple.  There is zero benefit for dynamic with virtualization
Can anyone point me to documentation on best practices for in-guest disk formats? I know the Compellent thin-provisions everything. However, in VMware 5.5, when setting up a virtual disk in the guest you have a number of choices:  Then again at OS level you have a choice of: I would appreciate a pointer to technical document explaining the benefits/drawbacks of each choice and recommended best practice. Kind Regards, Kath    
Dell Compellent - VMware Virtual disk - Thin and Thick provisioned - Basic and 
Dynamic disks - best practice