Andres Cheah

VMware ESX and VMware ESXi are bare metal embedded hypervisors that are VMware's enterprise software hypervisors for guest virtual servers that run directly on host server hardware without requiring an additional underlying operating system.

The basic server requires some form of persistent storage (typically an array of hard disk drives) that stores the hypervisor and support files. A smaller footprint variant, ESXi, does away with the first requirement by permitting placement of the hypervisor on a dedicated compact storage device. Both variants support the services offered by VMware Infrastructure.

Please note that if you experience an issue (hang / stuck / slow) while restarting your ESXi host(s), this issue is due to USB Arbitrator service which manages USB pass-through. This service does not support simultaneous USB connections both from USB devices and from USB service console.

One of the options to solve this issue is by waiting the host to boot up and disabling USB arbitrator service auto-start on next reboot at the ESXi console:

chkconfig usbarbitrator off

Otherwise, you can reboot the host, actually for me once booted up host it worked fine, so if you need to disable USB arbitrator service without rebooting:

service usbarbitrator stop

References:

1.  VMware vSphere® 5.1 Release Notes

http://www.vmware.com/support/vsphere5/doc/vsphere-esx-vcenter-server-51-release-notes.html#whatsnew

2.  ESXi 5.1: Stuck on running usbarbitrator start

http://hostilecoding.blogspot.com/2013/02/esxi-51-stuck-on-running-usbarbitrator.html

3.  VM ESXI 5.1 hangs when starting vmfs3 loaded successfully

http://community.spiceworks.com/topic/336178-vm-esxi-5-1-hangs-when-starting-vmfs3-loaded-successfully