(mysql.info) innodb-checkpoints

 
 14.2.8.2 Checkpoints
 ....................
 
 `InnoDB' implements a checkpoint mechanism known as `fuzzy'
 checkpointing.  `InnoDB' flushes modified database pages from the
 buffer pool in small batches. There is no need to flush the buffer pool
 in one single batch, which would in practice stop processing of user
 SQL statements during the checkpointing process.
 
 During crash recovery, `InnoDB' looks for a checkpoint label written to
 the log files. It knows that all modifications to the database before
 the label are present in the disk image of the database. Then `InnoDB'
 scans the log files forward from the checkpoint, applying the logged
 modifications to the database.
 
 `InnoDB' writes to its log files on a rotating basis. All committed
 modifications that make the database pages in the buffer pool different
 from the images on disk must be available in the log files in case
 `InnoDB' has to do a recovery. This means that when `InnoDB' starts to
 reuse a log file, it has to make sure that the database page images on
 disk contain the modifications logged in the log file that `InnoDB' is
 going to reuse.  In other words, `InnoDB' must create a checkpoint and
 this often involves flushing of modified database pages to disk.
 
 The preceding description explains why making your log files very large
 may save disk I/O in checkpointing. It often makes sense to set the
 total size of the log files as big as the buffer pool or even bigger.
 The drawback of using large log files is that crash recovery can take
 longer because there is more logged information to apply to the
 database.
Info Catalog
(mysql.info) forcing-recovery
(mysql.info) innodb-backup
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