Thursday, August 28, 2008

Technical differences between VMware ESXi and ESX

I have spent some time with looking for more details about VMware ESXi compared to VMware ESX. I summarized the main differences in this article but I think it's not complete. There have to be more features missing in ESXi because of service console removal. So, what next did I discover?
  • ESXi is supported on smaller set of certified hardware because it is standalone system and it doesn't depend on RHEL service console which provides drivers for other hardware.
  • You can manage ESXi with RCLI on Linux or Windows platform but Virtual Infrastructure client is more comfortable and easier to use. Further, if you deployed ESXi without Virtual Infrastructure licence, RCLI will have read-only access only. The drawback of VI client is that it is available for Windows platform. The solution may exist in using Wine emulator but the installation isn't as straightforward as on Windows plartform. The Wine application database contains this entry about VI client installation but I haven't tried it yet.
  • You can manage your ESX server directly via serial cable but ESXi is missing this feature.
  • ESXi kernel is missing jumbo frames support in TCP/IP stack which allows to send larger frames out onto physical network. It can help to achieve higher throughput with NFS or iSCSI protocols.
  • ESXi doesn't support NetQueue technology which is boosting 10G Ethernet performance.
  • Finally, VMware in cooperation with Mellanox Technologies supports Infiniband host channel adapters on ESX. ESXi is missing it.
The previous six points are related to the technical aspects of ESX and ESXi hypervisor. These points aren't complete as well but they are quite important for common deployment of VMware technologies. If you know about something else, please share it at my blog. For further information, check these links:
  1. VMware ESX 3.5 release notes
  2. VMware ESXi 3.5 release notes
  3. ESX and ESXi comparison (VMware knowledge base)
  4. Differences between ESXi and ESX (VMware knowledge base)

1 comment:

Chetan Venkatesh said...

One of the most significant frustrations of using ESXi instead of ESX (and in my mind validates the adage - you get what you pay for) is what we've called the ESX Root Lockdown problem at my company.

ESXi can erratically hang due to a bug where it internally writes to a non existent partition. There is no way to contact or communicate with the ESX server except physically reboot it. In previous versions this would hang all guest vms - a recent patch still hangs ESX while the GuestVms continue to run.

We've seen this happen sometimes upto thrice in one day on SATA based (vmware certified) servers with an LSI logic controller. Needless to say in a data center - these kinds of breakdowns can causes endless furstration and time loss.

Palo Alto, CA