• ATS - Atomic Test & Set - HardwareAcceleratedLocking on Single Extent Datastore or on Multi Extent Datastore (SCSI code 0x89)
• Extended copy - HadwareAcceleratedMove (SCSI code 0x83)
• Write Same - HadwareAcceleratedInit or Zeroed out blocks (SCSI code 0x93 or 0x41)
• Block Delete - UNMAP (SCSI code 0x42)

For more information on ESXi 5.5, see Using esxcli in vSphere 5.5 to reclaim VMFS deleted blocks on thin-provisioned LUNs (2057513).

• press u to get the disk device view.
• press f, o & p to select VAAISTATS and VAAILATSTATS/cmd fields.

You see the different counters in the column heads which can be split into different categories:

• ATS - Atomic Test & Set
  
  ATS – The number of ATS commands successfully completed
  ATSF – The number of ATS commands failed
  AAVG/suc – The Average ATS latency per successful command
  AAVG/f – The Average ATS latency per failed command
  
  
• Extended Copy
  
  Clone_RD – The number of CLONE commands successfully completed where this device was a source.
  Clone_WR – The number of CLONE commands successfully completed where this device was a destination
  Clone_F – The number of failed CLONE commands
  MBC_RD/s – The megabytes of clone data read per second
  MBC_WR/s – The megabytes of clone data written per second
  AVAG/suc – The average clone latency per successful command
  AVAG/f – The average clone latency per failed command
  
  
• Write Same
  
  Zero – The number of ZERO commands successfully completed
  Zero_F – The number of ZERO commands failed
  MBZERO/s – The megabytes zeroed per second
  ZAVG/suc – The average zero latency per successful command
  ZAVG/f – The average zero latency per failed command
  
  
• UNMAP - Block Delete
  
  Delete – The number of successful DELETE commands
  Delete_F – The number of DELETE commands failed
  MBDEL/s – The rate at which the DELETE command getting processed which is measured in Megabytes per second