vGeek esxtop handbook

Document created by wen Employee on Feb 22, 2013Last modified by wen Employee on Nov 5, 2013
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Live document on tips and tricks of using 'esxtop' to monitor/troubleshoot storage performance issues in ESX


Chapter VAAI (vStorage API for Array Integration)


Type s, and then enter '2' to show stats on 2 second interval


What to know VAAI stats (i.e., how many ATS, WRITE_SAME zero out commands are issued/failed?)

Type 'u' to show all devices (all volumes provisioned to the host)



Type 'f'



Type 'o' to move the VAAI fields towards the front (unless you have a huge monitor)

Type 'O' until you see 'O' close to the front of the field order



Press Enter to see the refresh stats screen


The ones highlighted in red below are the ones specific to VAAI



XCOPY primitive stats (primitive is coming in future)

  • CLONE_RD-> read I/O offload (primitive coming in future)
  • CLONE_WR -> write I/O XCOPY  (primitive coming in future)
  • CLONE_F ->failed XCOPY cmmands (primitive coming in future)
  • MBC_RD/s & MBC_WR/s (throughput stats for XCOPY)


Hardware Assisted Locking stats

  • ATS->automatic test & set (h/w assisted locking)
  • ATSF->failed ATS (non-zero value doesn't mean you are screwed, but rather, it falls back to SCSI-2 reservation for metadata updates; might worth investigating if the value is in the hundreds AND you see 'scsi reservation conflicts' message in /var/log/vmkernel)


Block Zeroing primitive stats

  • ZERO->WRITE_SAME commands offloaded
  • ZERO_F->failed WRITE_SAME commands (again, not a critical situation if this is non-zero; but worth investigating if the number goes up every time a new VMDK is created)
  • MBZERO/s ->throughput for WRITE_SAME


SCSI UNMAP primitive stats

  • DELETE (UNMAP, space reclaimation - note this needs to be done manually using vmkfstools command)
  • DELETE_F (failed to reclaim space counter)
  • MBDEL/s (throughput for UNMAP)