安装mysql 报Fatal error: cannot allocate memory for the buffer pool

120710 11:01:38 InnoDB: Initializing buffer pool, size = 8.0G
InnoDB: mmap(8791261184 bytes) failed; errno 12
120710 11:01:38 InnoDB: Completed initialization of buffer pool
120710 11:01:38 InnoDB: Fatal error: cannot allocate memory for the buffer pool
120710 11:01:38 [ERROR] Plugin 'InnoDB' init function returned error.
120710 11:01:38 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
120710 11:01:38 [ERROR] Unknown/unsupported storage engine: InnoDB
120710 11:01:38 [ERROR] Aborting

从err日志，可以看出，我分配的Initializing buffer pool, size = 8.0G，使得机器无法初始化。导致mysql启动不起来。

这个值=>my.cnf的innodb_buffer_pool_size

只要重新设置innodb_buffer_pool_size即可。官方文档默认值给出的是128M，如下图所示。

Name	Old Default	New Default
innodb_additional_mem_pool_size	1MB	8MB
innodb_buffer_pool_size	8MB	128MB
innodb_change_buffering	inserts	all
innodb_file_format_check	ON	1
innodb_log_buffer_size	1MB	8MB
innodb_max_dirty_pages_pct	90	75
innodb_sync_spin_loops	20	30
innodb_thread_concurrency	8	0