determining root cause of inconsistent hard drive performance?
Posted by:
jim bean
Date: January 10, 2012 04:43PM
Hello!
I'm experiencing an issue with my MYSQL server. In a nutshell, queries and writes (from CSVs) run roughly twice as fast off one hard drive (lets call Drive-A), as they do on another (let's call Drive-B). However, in benchmark tests on the drives (through hdparm and dd and bonnie++), Drive-B outperforms Drive-A in both read and write performance!
Both drives are ext4 with the same parameters.
The same database and data is used on both drives with identical .my.cnf configuration (aside from the mysql_data etc. directories)
Some extra information: when running 'iostat -x' while loading CSVs the "avgrq-sz" is only ~55, and it's much larger when doing manual DD tests (around 200)
The OS is RHEL 6.1 x64, with mysql-5.5.16-linux2.6-x86_64
Any ideas what might be causing this discrepancy in performance? Thank you in advance for any help
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determining root cause of inconsistent hard drive performance?
January 10, 2012 04:43PM
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