If you have been following on VMware vSphere closely, then you would know that VMware VAAI(vStorage Api for Array Integration) is evolving to be more important on regular basis. VAAI, as you probably aware is a method VMware use to offload some tasks to the storage. The initial release was to offload three main functionality:

1- Full Copy: It was used to offload copying VMs to the storage to handle it rather than doing it in the software. This speed up VMs Deployment & so on.

2- Zero Blocks: which is used to zero-out disk regions

3- VMFS Assisted locking, so ESXi hosts will lock only a block rather than the full store as originally was the case before introducing VAAI when any file operation was done.

EMC VPLEX Metro Storage clustering with vSphere has been getting a lot of interest lately. Many companies are interested of building a Disaster Avoidance & Across Site Availability scenarios where EMC VPLEX with vSphere stretched cluster might seems to be the easy solution to do it. Ok,  if you told me this about a year back I would told you about all the draw backs about this approach and all kind of deadly loop holes that could made the solution a disaster like if the links between the two sites failed or a full site failure. The good news that EMC & VMware has already addressed most of these with the vSphere 5 & the new EMC VPLEX 5 (Is it a conscidence that both products are at version 5 or was it a good planning between the two companies I really don’t know the truth on that).