I’ve talked about VAAI a few times in my blog (such as VAAI implementation on the P2000 and vSphere), but what is it?
A quote from VMware:
Storage APIs deliver tight integration of advanced capabilities from storage partners with the Virtual Datacenter OS from VMware. vStorage APIs for array integration will enable customers to leverage array-based capabilities, such as snapshots, provisioning, replication and restore, directly with individual virtual machines in conjunction with the clustering and pooling capabilities of VMware Infrastructure. vStorage APIs for multi-pathing will provide customers the ability to integrate advanced load balancing capabilities provided by leading partners’ multi-pathing software with their virtual environment.
VAAI, vStorage API’s for Array Integrators, is enabled in the firmware of different vendor devices to offload some of the host tasks directly to the storage array. Its starting to be seen more and more now as vendors support it in their newer storage devices and firmware offerings. What features do you get with VAAI and which will make a difference?
Offloaded Copy – Up to 10 x faster deployments of VM’s, Storage vMotion & Cloning. VAAI offloads the copy tasks direct to the array, enabled the use of the native storage functions, leading to a decrease in deployment time, but also reducing the amount of data passing between the host and the array.
Write Zero/Same – I/O for common tasks can be reduced by 10x. For example, zero-out processing takes less time as the storage array repeats the same scsi command rather than the host, reducing the load on the server and decreasing the time taken to complete.
Offload Locking – Locking is offloaded to the array, which is known as Atomic Test & Set. This helps to reduce latency where thin provisioned, snapshots and linked clones are utilized. With ATS it removes the need to lock the entire VMFS but instead only locks a block when an update occurs.
Some really good in-depth articles on VAAI below:
VMware KB – VAAI FAQ
Matt Liebowitz – Exploring the performance benefits of VAAI
VMware Support Blog – VAAI changes the way storage is handled
Chad Sakac – What does VAAI mean to you?
Bas Raayman – What is VAAI, and how does it add spice to my life as a VMware admin?