vsphere-esxi-vcenter-server-55-storage-guide

vSphere StorageHardware Acceleration RequirementsThe hardware acceleration functionality works only if you use an appropriate host and storage arraycombination.Table 24‐1. Hardware Acceleration Storage RequirementsESXi Block Storage Devices NAS DevicesESX/ESXi version 4.1ESXi version 5.xSupport block storage plug-ins forarray integration (VAAI)Support T10 SCSI standard or blockstorage plug-ins for array integration(VAAI)Not supportedSupport NAS plug-ins for arrayintegrationNOTE If your SAN or NAS storage fabric uses an intermediate appliance in front of a storage system thatsupports hardware acceleration, the intermediate appliance must also support hardware acceleration and beproperly certified. The intermediate appliance might be a storage virtualization appliance, I/O accelerationappliance, encryption appliance, and so on.Hardware Acceleration Support StatusFor each storage device and datastore, the vSphere Web Client display the hardware acceleration supportstatus.The status values are Unknown, Supported, and Not Supported. The initial value is Unknown.For block devices, the status changes to Supported after the host successfully performs the offloadoperation. If the offload operation fails, the status changes to Not Supported. The status remains Unknownif the device provides partial hardware acceleration support.With NAS, the status becomes Supported when the storage can perform at least one hardware offloadoperation.When storage devices do not support or provide partial support for the host operations, your host reverts toits native methods to perform unsupported operations.Hardware Acceleration for Block Storage DevicesWith hardware acceleration, your host can integrate with block storage devices, Fibre Channel or iSCSI, anduse certain storage array operations.ESXi hardware acceleration supports the following array operations:• Full copy, also called clone blocks or copy offload. Enables the storage arrays to make full copies of datawithin the array without having the host read and write the data. This operation reduces the time andnetwork load when cloning virtual machines, provisioning from a template, or migrating with vMotion.• Block zeroing, also called write same. Enables storage arrays to zero out a large number of blocks toprovide newly allocated storage, free of previously written data. This operation reduces the time andnetwork load when creating virtual machines and formatting virtual disks.• Hardware assisted locking, also called atomic test and set (ATS). Supports discrete virtual machinelocking without use of SCSI reservations. This operation allows disk locking per sector, instead of theentire LUN as with SCSI reservations.Check with your vendor for the hardware acceleration support. Certain storage arrays require that youactivate the support on the storage side.236 VMware, Inc.