Servers with IPMI functionality let netwoide of transaction) will need to flush log to the disk which is rather expensive, especially if you do not have Battery backed up cache.

• 默认值是1，这意味着每次提交的更新事务（或者每个事务之外的语句）都会刷新到磁盘中，而这相当耗费资源，尤其是没有电池备用缓存时。