Tag Archives: average

Hidden VNXe performance statistics revised


In my previous post covering the VNXe hidden statistics I explained where to find the “hidden” statistics files and how to extract the data into usable format. Now it seems that EMC has changed the statistics gathering interval from 5 minutes to 30 minutes. I started playing around with the new data and created a spreadsheet template that generates graphs for IOps and MB/s for the past 2 months, 1 month, 2 weeks, 1 week and 24 hours. In this post I will share the template and also explain how to use it.

Exporting data from SQLite database and importing it into the spreadsheet

The first two steps are explained in more detail in my previous post

  • Get stats_basic_summary.db and old.stats_basic_summary.db files from VNXe
  • Export data from those files to stats_basic_summary.txt and old.stats_basic_summary.txt files.
  • Download the spreadsheet template from here. (I have tested it with OpenOffice and Microsoft Excel and it works better with Excel. I was planning to use Google Docs but there is just too much data on the spreadsheet so it didn’t work.)
  • Import stats_basic_summary.txt content into the spreadsheets stats_basic_summary.db sheet starting from A1 and using Delimited data type and tab + comma delimiters

  • Import old.stats_basic_summary.txt content into the spreadsheets old.stats_basic_summary.db sheet starting from A1 and using Delimited data type and tab + comma delimiters

If you now go to the “2 months” sheet the graphs might look like this:

Removing zeros from the statistics

Sometimes VNXe seems to fail updating the statistics to the database and only zeros are added. When using the data without taking the zeros out it will produce graphs as shown above. Rows 43-2772 on the imported sheets are used for the statistics and it is important to find all zero rows to get the graphs working properly.

Data from the previous row should be copied to replace the zeros from column D onward. All the statistics values seem to be running numbers and for the graphs the latter value is deducted from the previous value. So replacing the zeros with the value from previous row will make the particular timestamp to be zero on the graph.

After all the zeros are replaced in most cases the statistics and graphs will show the correct values.

Performance counters reset during the data gathering

If the statistics and graphs are still not showing the correct values after removing the zeros from the data the issue might be that the performance counters were reset during the data gathering period. When this happens there might be a row of zeros before the reset.

To fix this the zero row should be replaced as described above and the row below the zeros should be deleted.

Disclaimer

This method for gathering and presenting the statistics is not approved or confirmed by EMC. This is something I have found and it seems to work in the environments I work with. So the statistics might not be accurate.

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