Amazon EBS + MySQL Performance
We have switched to an EBS deployment to make sure our databases are always backed up and can start a new EC2 instance very quickly from the EBS instance if needed. The first day into the switch, some transactions started performing poorly - from under 1 second to 20 seconds. When we compared the timings from the previous logs almost all transactions had a dip in performance from about double to 20 times.
What we noticed is a large number of small disk writes affects the whole disk performance, for read transactions as well. These writes are coming from log file entries - apache & tomcat logs. Once these are moved out of EBS the performance is back to normal and in some cases better than before. Looks like it is better to have a separate EBS instance for the database - database writes do not seem to have such adverse impact.
