Dell EMC Metro node 7.1 Administrator Guide

Hardware acceleration with VAAI

VMware API for Array Integration (VAAI) allows you to:

Offload storage operations from compute side to storage hardware.
Shift I/O intensive operations of provisioning and creating a snapshot from hypervisor to metro node.
Dedicate hypervisor memory and processing resources to other functions.
UNMAP unused storage blocks from thin provisioned volumes. Thin support in metro node Provides more information on thin provisioning.

VAAI is implemented in metro node using four SCSI commands:

“Compare and Write” offloads coordination of powering virtual machines (VMs) on/off, and moving them between hypervisors.
“WriteSame (16)” offloads writing same pattern of data, such as zeroing out blocks for disk initialization.
XCOPY offloads copying data to and from the array through the hypervisor.
Enabling and disabling XCOPY using CLI provides more information on enabling and disabling XCOPY.
UNMAP allows the hypervisor to reclaim deleted storage on thin-provisioned metro node virtual storage. See "Understanding Thin Provisioning" for more information on thin-provisioned volume and UNMAP functionality.