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High Av Rd(ms)

Article by Rampant Author Brian Carr

If you are seeing high Average Disk Read times in your Oracle AWR Report read this tip.

High Average Disk Read times can be seen under the Tablespace IO Stats section of the AWR Report. When you see Av Rd(ms) of greater than 7 ms you may have an issue that requires further investigating. This could mean your system is experiencing extremely slow Avg Read times from the disk subsystem.

In addition to SQL tuning of high-impact statements, the disk subsystem may need tweaked. This following disk setup would help with scattered and sequential disks reads. Additionally it would allow log switches to occur more rapidly.

Some considerations to make when purchasing an alternative storage solution are:

  • At least 512MB cache on Raid controllers, BBWC (battery backed write cache)
  • RAID Setup must be RAID 10 (Oracle Best Practice) - Don't let your SAN Admin tell you its too expensive. So is your time and all the users who are going to suffer from a poor disk setup....
  • Number of spindles (the more the better)





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