Identify storage performance issues

VMware has recently updated the kb article “ Using esxtop to identify storage performance issues
” (KB1008205).
The KB article provides information about how to use esxtop to determine the latency statistics across various devices. The article contain easy to follow, step-by-step instructions on how to setup ESXtop to monitor storage performance per HBA, LUN and virtual machine. It also list generic acceptable values to put your measured values in perspective. It’s a great article, bookmark it for future reference.

If you want to learn about threshold of certain metrics in ESXtop, please check out the ESXtop metric bible featured on

ESXtop is a great tool to view and measure certain criteria in real time, but sometimes you want to collect metrics for later reference. If this is the case, the tool vscsiStats might be helpful. vscsiStats is a tool to profile your storage environment and collects info such as outstanding IO, seekdistance and many many more. Check out Duncan’s excellent article on how to use vscsiStats.

Because vscsiStats will collect data in a .csv file you can create diagrams, Gabe written an article how to convert the vscsiStats data into excel charts.


  1. Hi Frank, thanks for the info. The KB link seems to be broken, though…

  2. frankdenneman

    March 25, 2010 at 13:09

    Hi Loren,

    Thanks for the heads-up, I fixed the link.
    It should work now

  3. Craig Risinger

    March 25, 2010 at 20:30

    Esxtop also runs in “batch” mode where it outputs metrics to a .csv file. Each row is a snapshot that has one column per metric.
    -b = batch mode
    -a = get ALL metrics (not just the default subset)
    -n # = run for # of snapshots before stopping automatically (nice for running from crontab and not have to manually kill the process when done)
    -d # = wait a delay of # seconds between performance snapshots

    Be warned, though, if you use -a you will get many thousands of columns, and Excel won’t open it. Try using esxplot instead to open it. Alternatively, choose just the fields you want and save that in an esxtop.cfg file and specify that.

  4. frankdenneman

    March 25, 2010 at 23:44

    Excellent stuff! Thanks Craig!

  5. Hi Frank!

    Some greath articles on you site here! I have written something about ESX and performance logging as wel. You or some of your readers might find it valuable.

    Keep those post comming!



Comments are closed.

© 2018

Theme by Anders NorenUp ↑