Quick Hit - New vSphere 4 Storage Features

Paravirtualized iSCSI

What: This is a driver for high performance storage adapters

Benefits: It offers greater throughput and lower CPU utilization

When to use it: For very I/O intensive applications

VMDirect I/O for Storage

What: Enables VMs to directly access the underlying hardware

Benefits: Enhances CPU efficiency in applications with constant and frequent I/O

Drawbacks:
     1) VMotion is not available
     2) HBA is not shareable by other VMs

Virtual Disk Thin Provisioning

What: Space is allocated on an as-needed basis in 1 MB chunks

Benefits:
     1) Improves storage efficiency
     2) Increases utilization rates
     3) Reduces storage costs

Drawbacks: You could over provision the disks and run out of space, so monitoring of resources is essential.