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We currently run one instance of VMWare ESX server, but want to start virtualizing more physical hardware with VMWare, while keeping the cost of VMWare licensing as low as possible.

Is ESXi a good option or do we need purchase a new license for ESX for each physical box? What are the benefits/limitations of ESXi vs ESX?

Our guest OS's are Windows 2003/2008.

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  • The main difference is that ESXi comes without service console. I.e. it has a smaller footprint and therefore the attack surfaces is also smaller which is good if you don't like installing security patches (there are many security related updates for the packages that come with the Linux-based service console). The service console also makes it possible to execute scripts and install third party agents (for monitoring, backup, etc.).
  • ESXi does not support VI Web Access.

Here's a nice VMware knowledge base article: VMware ESX and ESXi Comparison

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ESXi not having a service console ... is not exactally true. It exists, is more limited than ESX, but it is there. – Zypher Jan 19 '10 at 22:17
@Zypher - The service console is a hidden virtual machine that runs on ESX. ESXi does not have the service console. What you connect to on ESXi is a lightweight shell on the vmKernel. – JakeRobinson Feb 19 '11 at 20:19

Found this VMware ESX and ESXi 4.0 Comparison

The one from @knweiss was for version 3.5

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ESX is also being depreciated. I believe ESX 4.1 is the last full version of ESX that will be released. All versions going forward will be ESXi-only. So if VMware's future is riding on ESXi, it's reasonable to assume so should yours.

Here's a blog post on ESX's sunset:

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Yes, 4.1 will be the last full version of ESX out. 4.1 has quite a few changes from 4.0 u2 so I think 4.1 can be thought of as ESXi I read. – Chadddada Feb 16 '11 at 2:14

As it was stated above ESX as we know it, and you run, is going away. Having only 1 host you are not heavily invested so it would probably be a great time, if you are going to really jump into the P to V conversion, to just plan for ESXi. There have been some great blogs, articles, and posts going up lately so you may want to read them. A couple that are pretty decent are:



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Having trialled beta code of vSphere 5.0 for a while now I'm 100% certain everyone needs to move to ESXi for all new installs as it'll prepare people for losing their consoles.

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Is there any place that us System Administrators, who are not in the vSphere 5.0 beta, can get more information on the product? Most of the discussion online appears to be around speculated release dates and some of the features that will be available. – Chadddada May 9 '11 at 18:04
I'm NDA'ed up sorry. – Chopper3 May 9 '11 at 18:05
Not a problem and understandable! – Chadddada May 9 '11 at 18:35

The big benifit of ESX over ESXi is with ESX you can use Virtual Center to manage everything form a single location (Virtual Center is an additional one time cost).

If you are using SAN storage, you can use Virtual Center to create an ESX cluster which will dynamically move guests from one node to another as needed for performance without any down time (you can control how aggressively this is done).

With ESXi you can't use Virtual Center to manage the host so you have to manage each host independently. With 1 or 2 hosts this isn't that bad, but as you get more hosts it becomes a pain having to remember which host a VM is one. With Virtual Center you group everything into a datacenter and everything is presented as a single resource pool.

In addition with Virtual Center comes a license for the VMware converter, and the ability to create templates which make creating new VMs a 5-10 minute process to spin up a new Windows VM with the OS already installed.

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vCenter does support ESXi hosts, too. However, to manage an ESXi host with vCenter Server, you must have a vCenter Server Agent license, which is included in all editions of VMware vSphere. – knweiss Jul 15 '09 at 18:36
If I remember correctly ESXi can be managed by vCenter, but only as a read only server. To be able to create VMs on an ESXi you have to connect to the server don't you? – mrdenny Jul 16 '09 at 0:57
@mrdenny, vCenter can manage ESXi servers and create new VMs on them. – Keith Sirmons Jan 8 '10 at 7:22
Multiple incorrect statements in this answer. 1. Both ESX and ESXi have always had the ability to be managed by VC. 2. You are not limited to a single "resource pool" in VC. 3. VMware converter is free. – JakeRobinson Aug 1 '10 at 6:19
ESXi is also managed by vCenter. – Chadddada Feb 16 '11 at 2:15

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