[GRLUG] FYI - old mysql and new gear

[scott.tanner at comcast.net]

Just thought I'd share an interesting discovery with the group. This may be common knowledge to others, but it was a bit of a surprise to me. We're in the process of upgrading the servers which run our primary MySQL DB's (version 5.1): 

Old Server New Server 
--------------------------------------------------------- 
Sun X4200 Silicon Mechanics R516 
4 x 2.4GHz 12 x 3.2GHz (+ HT = 24 threads) 
16GB Ram 144GB Ram 
12 disks - SCSI 24 disks - SAS & SSD 


After getting the new servers setup and our databases copied over, I ran sysbench to get some performance benchmarks of the new servers. Surprise - performance was nearly identical or slightly worse. I disabled HT, still no real improvement. After a bit of searching on the web, I found the older versions of MySQL had issues with multi-threading beyond 8 threads. I setup an init script to hot-remove CPU's via sysfs, and voila - performance increased substantially. There are patches from Yahoo, Google, and Percona to correct this issue on the older MySQL versions, and the newer versions are supposedly better at handling 32+ threads. 


Regards, 
Scott 

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