Understanding the Role of IO As a Bottleneck

This talk is aimed at beginner-intermediate DBAs looking to understanding the role of IO (disks, SSDs) as part of the bigger picture of system performance.

We start by looking at how buffered IO works, and what the difference is between writing and syncing, and then we look at interpreting output from Linux diagnostic tools such as iostat under some typical workloads (read heavy, write heavy, data fits in buffer pool versus does not).

Once we’ve mentioned which situations IO is a problem, we look at some of the common options available to improve the situation – RAID, Raid controllers with battery backed write caches and SSDs.

Also explained will be when to enable options like innodb_flush_method=O_DIRECT, and what last gallant efforts (if any) you can make if you are IO bound but can’t yet upgrade hardware.