The unsung heroes of InnoDB are the logfiles. They are what makes InnoDB automatic crash recovery possible.Database administrators of other DBMS may be familiar with the concept of a "redo" log. When data is changed, affected data pages are changed in the innodb_buffer_pool. Then, the change is written to the redo log, which in MySQL is the InnoDB logfile (ib_logfile0 and ib_logfile1). The pages are marked as "dirty", and eventually get flushed and written to disk.If MySQL crashes, t