HP 3PAR Solutions Software for vSphere - Manual (Page 13)

2.3 About 3PAR VAAI Plug-in 1.1.0 for VMware vSphere 4.1
3PAR VAAI Plug-in 1.1.0 for VMware vSphere 4.1 Users Guide
2.2.1 Hardware Assisted Locking (ATS)
Rather than locking the entire LUN, Hardware Assisted Locking (ATS) only locks the blocks on
the LUN that are allocated to the VMDK. This enhanced capability is intended to help
virtualized data centers in at least two important ways.
■ If you are already using or want to use larger size LUNs and place multiple VMDKs on a
single LUN, you can now do so and still make clones of individual VMDK files without
negatively impacting other VMDKs also located on that LUN.
■ 3PAR's implementation of the ATS command was done within the ASIC of its InServ Storage
Servers to expedite processing of this command. While the performance benefits this
provides in small environments may be too negligible to notice, large virtualized
infrastructures can quickly create large numbers of clones.
3PAR’s unique implementation of Hardware Assisted Locking takes advantage of the 3PAR
Gen3 ASIC to handle data comparisons in silicon with significantly higher performance and
throughput. It facilitates the automatic modification of disk sectors without the use of SCSI
reservations so multiple hosts can access LUNs concurrently while reducing the number of
commands required to successfully acquire on-disk locks.
2.2.2 Full Copy (XCOPY)
Full Copy (XCOPY) resolves the host overhead that is associated with VMware initiating and
managing cloning operations. It facilitates the cloning of individual VMDKs while keeping the
overhead associated with the copy off the host and on the storage array which can
significantly improve the performance of host-initiated clones.
Full Copy increases agility by reducing the amount of time required to perform common copy
operations like virtual machine cloning and storage workload migrations using VMware
Storage vMotion™. This is made possible by allowing the storage hardware to transparently
manage large data movements, and by minimizing host, fabric and network I/O activity. With
the integration of the 3PAR Gen3 ASIC and 3PAR Thin Persistence software, built-in zero-
detection capabilities further speed cloning and storage workload migrations while also
delivering a capacity savings benefit.
2.2.3 Block Zeroing (WRITE-SAME)
Block Zeroing (WRITE-SAME) is intended to reduce the host overhead that results when
VMware zeros out disk space for Thin and Thick VMDKs and at create time for VMs.