Hi Ram,
First of all vsphere replication as mechanism is totally different than array based replication. The first one is synchronous and the second one - asynchronous.
>> what is the minimum time required to bring up the vms in DR site in case my DC is totally failed .(using Vspehre replication & Storage replication )
In both cases this depends on what is running on your machines. Since on the recovery site you have a powered off machine (either a placeholder VM or bunch of files that to be registered as a VM) the power on process depends on software. In case the VMs are replicated with quiescing enabled then some of the software (that supports it) will be up very quickly.
>>what is the data loss in case my primary is down at point ( using Vspehre replication & Storage replication )
With vSphere Replication your RPO is between 15 mins and 24 hours - depending on your configuration (this is because of the synchronous replication). With array based replication I'm not aware of the data loss.
>> what are the other advantages and real benifits in a DR Prospective .
One of the benefits of VR is that you are able to replicate within the same vCenter server between hosts/datastores
VR is available as a standalone feature of vSphere suite and as a feature of Site Recovery Manager, while array based replication is only available through Site Recovery Manager. Also VR is storage agnostic while array based is not and required compatibility between SANs
More thorough comparison can be seen here VMware SRM: vSphere Replication vs. Array Based Replication - viktorious.nl - Virtualization & Cloud Management
Regards,
--Martin