I spent some more time today comparing InnoDB and MyISAM on SSD.
I increased the data/cache ratio by about 5X. I allocated 1G of memory for MyISAM or InnoDB (restating MySQL after each test). Resulting on disk images are 6G for MyISAM and 7G for InnoDB.
This is on a 30M row DB which stores ints and char data.
I’m primarily testing the theory that SSD could be used to get near in-memory performance by using cheap SSDs since they can do lots of random reads.
MyISAM would clearly outpace InnoDB if I would perform the initial ‘prepare’ (bulk insert) stage in multiple processes. MyISAM became CPU bottlenecked which ended up slowing the write rate.
InnoDB on the other end had the SSD at 100% utilization. I’m not sure why. It could either be an issue with the 16k page size or the write ahead log.
A 3x performance boost is more than acceptable here especially when you consider you can create a 96G SSD RAID array for the same price as 8G of RAM.
I might end up recompiling MySQL with an 8k and 4k page size for InnoDB just to see if it makes any difference.
Further, I might spend some time trying to figure out why InnoDB is so slow at performing the initial INSERTs.
Figure 1: MySQL performance time for sysbench for inserting and performing OLTP queries on the data. Times are in minutes (lower is better)
