VMware vSphere is the first cloud computing systems in information technology industry. There is no doubt about ESX’s reliability and performance. With the release of ESX 4.0 aka vSphere, there will be few features inbuilt into ESX 4.0 and rest are add on depending on how deep is your wallet.
vSphere basic components are VMware ESX or VMware ESXi hypervisor, VMware VMFS, VMware vSphere Client, Four-way vSMP support. ESX products are divided in two categories with sub-categories based on customer needs and affordability.
Figure: ESX Product comparison source http://www.vmware.com
ESX aka vSphere small business product is available in Essentials and Essential Plus sub-category. These are bundled products with targeting small business customer who aren’t willing to spend money but to have virtualized servers. Hence saving money for hardware and management cost. These version of license doesn’t contain any DRS, vMotion, hot Add, vShield luxury. But it works perfect if you want to virtualize 20+- servers. You can have maximum 3 ESX hosts with 2 processors each up-to 6 core per processor. ESX small business editions are priced in-between USD995 to USD2995. Essential got an year support within price. But you have buy additional support for Essential Plus and it’s mandatory. I reckon, Mr Paul Maritz released these editions to target Microsoft Hyper-v and off course you can use ESX without getting your hand into wallet i.e. ESXi single server version without spending $$$.
vSphere Editions sub-divided into standard, Advanced, Enterprise and Enterprise plus categories. These four editions got variety of flavour a VMware Administrator wants to play with. VMware data recovery, fault tolerance, hot add, Host profiles, thin provisioning, vNetwork distributed switch, vSheild Zones, DRS, DPM, vMotion and lots more. You can have these cool features based on your need and $$$$. vSphere editions are priced from US$795/processor (six core/processor) to US$2875/processor (six core/processor). A minimum one year support agreement is required with all vSphere products.
To deploy ESX with complete functionality you must have vCentre server and SAN. You can manage, update, secure, provision and orchestrate any operation through vCentre. You have to purchase vCentre Server separately to do all cool stuff.
In conclusion, I would recommend investigating individual need and business objectives. It’s good to have a business case and technical overview what you are going to achieve after spending on hardware and hypervisor.