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Death of the Storage Array

When I wrote this article for The Register in October 2010, there was a torrent of naysayers and witch hunters spewing their opinions in the comments section. I don’t have a problem with that, I was only expressing an opinion myself, after all. I don’t actually own a time machine and so any of my … Continue reading "Death of the Storage Array"

Death of the Storage Array

When I wrote this article for The Register in October 2010, there was a torrent of naysayers and witch hunters spewing their opinions in the comments section. I don’t have a problem with that, I was only expressing an opinion myself, after all. I don’t actually own a time machine and so any of my … Continue reading "Death of the Storage Array"

Death of the Storage Array

When I wrote this article for The Register in October 2010, there was a torrent of naysayers and witch hunters spewing their opinions in the comments section. I don’t have a problem with that, I was only expressing an opinion myself, after all. I don’t actually own a time machine and so any of my … Continue reading "Death of the Storage Array"

Analyzing IO at the Exadata Cell level… iostat summary

While analyzing Write-Back cache activity on Exadata storage cells, I wanted something to interactively monitor IO while I was running various tests.  The problem is summarizing the results from ALL storage cell.  So, I decided to use my old friend “iostat” and a quick easy script to roll up the results for both DISK and FLASH.  This allowed me to monitor the IOPS, IO size, wait times, and service times.  

The “iostat-all.sh” tool shows the following data:

Analyzing IO at the Exadata Cell level… iostat summary

While analyzing Write-Back cache activity on Exadata storage cells, I wanted something to interactively monitor IO while I was running various tests.  The problem is summarizing the results from ALL storage cell.  So, I decided to use my old friend “iostat” and a quick easy script to roll up the results for both DISK and FLASH.  This allowed me to monitor the IOPS, IO size, wait times, and service times.  

The “iostat-all.sh” tool shows the following data:

Dtrace probes in Oracle 12c… v$kernel_io_outlier is populated by dtrace!!

Oracle 12c certainly has some great features, but for the performance guy like myself, performance monitoring features are particularly interesting.  There are three new v$ tables that track anomalies in the IO path.  The idea is to provide more information about really poorly performing IO that lasts more than 500ms.

  • V$IO_OUTLIER : tracks the attributies of an IO.  The size, latency as well as ASM information is recorded.
  • V$LGWRIO_OUTLIER : tracks information specifically on Log writer IO.

These two tables are going to be useful to monitor when performance issues occur.  I can already see the SQL scripts to monitor this activity starting to pile up.  But, there is one little extra table that dives even further into the IO stack using Dtrace.

Dtrace probes in Oracle 12c… v$kernel_io_outlier is populated by dtrace!!

Oracle 12c certainly has some great features, but for the performance guy like myself, performance monitoring features are particularly interesting.  There are three new v$ tables that track anomalies in the IO path.  The idea is to provide more information about really poorly performing IO that lasts more than 500ms.

  • V$IO_OUTLIER : tracks the attributies of an IO.  The size, latency as well as ASM information is recorded.
  • V$LGWRIO_OUTLIER : tracks information specifically on Log writer IO.

These two tables are going to be useful to monitor when performance issues occur.  I can already see the SQL scripts to monitor this activity starting to pile up.  But, there is one little extra table that dives even further into the IO stack using Dtrace.