XenServer is free. vSphere is pricey, or so they say. You really need to compare feature by feature.
Some of the key features that virtualization users want are:
- Hypervisor (XenServer or vSphere)
- Central multi-hypervisor management (XenCenter or vCenter)
- If a physical host fails, restart virtual machines on surviving hosts (XenServer High Availability or VMware HA)
- Move a virtual machine from host to host while running (XenMotion or vMotion)
- Backup and recovery for virtual machines (No Citrix equivalent or VMware Data Recovery)
Citrix Xenserver is free. It includes XenMotion. To get HA, you need to buy Citrix Essentials for XenServer. I’m not aware of a Xen equivalent of VMware Data Recovery. List price on Essentials is $2750.
VMware offers a small business package called VMware vSphere 4 Essentials Bundle. This includes licenses for the hypervisor and management server (vCenter). The plain Essentials bundle does not include HA, vMotion, or VDR. The list price is $995.00.
You can get an upgraded Essentials, called VMware vSphere 4 Essentials Plus, that includes everything but vMotion for list $3624.
So what’s the bottom line? You probably *HAVE* to buy something. If you want high availability, then you have to buy Citrix Essentials or VMware Essentials Plus. The price is pretty similar ($2750 or $3624 list). If you go with XenServer, you’ll get XenMotion. If you go with vSphere, you get VDR.
Backup or the ability to move running machines? That’s a hard choice. You really need both in a production environment. Neither vendor at this entry price point offers everything you need.