How many Concurrent Jobs in vCenter Server we can run? Suppose VM power on Jobs?
Power on operations, the maximum is 50 per vcenter on version 5.x. There are other maximuns for vMotion, svMotion, etc, bue each depends if you see from a datastore perspective, or ESX perspective, or even vcenter perspective.
These limits are detailed in the Configuration Maximums whitepaper(s):
See original docs, plus a summary of differences;
http://www.jonmunday.net/2013/03/24/vmware-vsphere-5-x-configuration-maximums/