问:ESX 3.x和vSphere 4.0之间主要有什么不同?
答:vSphere 4.0较之之前的版本有很多新特性和架构上的变化。下面是其中一些主要的方面,或许对你部署vSphere时有所帮助。

架构性的改变

主要有3个改变:
(1) vDS,也就是vNetwork Distributed Switches.  这是一种下一代的虚拟网络解决方案,是一种集群级别的虚拟交换机(跨主机的虚拟交换机,而不是只能在每台主机上分别存在的传统的虚拟交换机)。不仅如此,它还是第三方分布式虚拟交换机的基石,例如现已可用的Cisco Nexus 1000v。
(2) PSA,全称Pluggable Storage Architecture.  它提供了一个开放的模块化框架,使得第三方可以为VMware提供多路径(Multipath)解决方案。例如EMC的Powerpath/VE。
(3) VMware VMsafe。它提供了一个新的防病毒和防火墙的解决方案,用了保护VMware环境中的虚拟机。

显著的特性改变

(1) FT – Fault Tolerance
(2) host profiles  
(3) thin-provisioning
(4) DPM – Distributed Power Management

其他改变

见以下原文


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Major differences of ESX 3.X and vSphere 4.0 

With the release of VMware vSphere 4.0, there are a lot of new features and architectural changes. Some of the new features and changes are minor, but the majority of them are significant. Covered below are some of the changes that you may need to know when you are deploying vSphere in your environment.  

Notable architectural changes 

The first architectural change that you will notice is vNetwork Distributed Switches. This is the next generation virtual networking solution. The vDS can span multiple hosts which enables you to reduce maintenance activities. In short, you can configure vSwitches on the cluster level instead of per host. This new architecture is also the foundation for third-party distributed vSwitches.  The first of these is the Cisco Nexus 1000v which is already available for use. 

The next new change is the Pluggable Storage Architecture (PSA). The PSA is an open modular framework that enables third-party storage multipathing solutions for workload balancing and high availability. A good example of a third-party solution is EMC’s Powerpath/VE which will automate and optimize server, storage and path utilization. The new architecture consists of several components. These components can be replaced individually by third-party modules or by an all in one multipathing plugin. 

The last but definitely not least notable change is VMware VMsafe.  VMware VMsafe is a new technology that leverages the properties of vSphere to protect virtual machines. The VMware VMsafe API enables partners to develop security related products. It provides transparency into the memory, CPU, disk and I/O systems of the virtual machine, and monitors every aspect of the execution of the system. This can provide a totally new approach for anti-virus solutions or firewalling for 
instance. 

Notable new features 

VMware Fault Tolerance (FT) is one of the most talked about new features, which provides stateful fail-over on a per virtual machine basis. There is no need to introduce it because everyone has seen the demos or tried it by now.   

A new feature that will make the life of many system administrators much easier is host profiles. Host profiles enable the user to configure a host via a policy. You can also use these policies to maintain consistency in your virtual environment.  

In ESX 4.0 you no longer need to resort to extending VMFS volumes when a volume runs out of disk space. The chances of running out of disk space without noticing have also been reduced by the added storage views, reports and alarms. One of the reasons these views, reports and alarms have been added is “thin provisioning”. This new GUI feature will enable you to quickly deploy virtual machines with a minimal disk size.  

Where ESX 3.0 and vCenter 2.0 had Distributed Resource Scheduling (DRS) as one of the most compelling features, vSphere has a fully supported version of Distributed Power Management (DPM). Wake On LAN, IPMI or iLO can be used to wake up any host when needed. When we are talking about TCO/ROI this is one of the features that can and will make a real difference. 

Obviously the feature list for vSphere 4.0 is huge and these are just some of the key changes we see that people are excited about. From the geek perspective, we also found the following “less pumped” features very cool and these features will improve usability and manageability: 

"      Improved centralized licensing functionality 
"      Up to eight virtual processors in a virtual machine (VM) 
"      Improvements to esxtop, which allow for more granularity 
       (such as the ability to determine which vmnic a VM is using!) 
"      Up to 255GB of RAM per VM 
"      Additional esxcfg-* commands.  
"      Per VMFS volume resignaturing 
"      Consolidated backup API 
"      Better granularity of security within vCenter (including datastores!) 
"      Granular permissions at the network and datastore level 
"      HA Maintenance mode 
"      Improved HA admission control 
"      VMkernel protection
"      New hardware/drivers such as VMXNET Generation 3, Paravirtualized SCSI (PVSCSI) 
"      Enhanced host power management 
"      iSCSI software initiator improvements 
"      Jumbo frame support for 1Gb and 10Gb NICs