Let me look at it from a server virtualization
perspective. The idea behind server virtualization is to create multiple logical "machines" on a single physical server. Suppose I have a single physical server and I create 20 virtual machines on top of that. If the server only has one or two HBAs
, and all of the storage is connected through those HBAs, there will be a serious I/O bottleneck at the storage controller. So bad in fact that IT folks had to reconsider the number of virtual machines they could apply to a server. This started to impact the server virtualization side. Without storage virtualization
, the industry has been addressing such bottlenecks using N_Port ID Virtualization (NPIV), which essentially divides the HBA into logical pieces that can be coupled to each virtual machine, eliminating the storage bottleneck.
Server virtualization vendors, like VMware, are becoming more sensitive to the storage needs of their virtual machines and are incorporating storage-centric features, such as virtual consolidated backup, or VCB, designed to make backups work across virtual machines without licensing and installing a unique copy of the backup software (e.g., EMC Legato) on each virtual machine. So a lot of work is being done to bring these two environments together, but this work is still in its infancy.
Check out the entire Storage Virtualization FAQ guide.
22 Aug 2007