| 8.000000000000 | +------------------------------------------+ 

In this example, innodb_buffer_pool_size  is set to 9G , and innodb_buffer_pool_instances is set to 16 . innodb_buffer_pool_chunk_size  is 128M , which is the default value. In this case, 9G  is not a multiple of innodb_buffer_pool_instances=16  * innodb_buffer_pool_chunk_size=128M , so innodb_buffer_pool_size  is adjusted to 10G , which is a multiple of innodb_buffer_pool_chunk_size  * innodb_buffer_pool_instances . 

shell> mysqld --innodb-buffer-pool-size=9G --innodb-buffer-pool-instances=16 

## Configuring InnoDB Buffer Pool Chunk Size 

mysql> SELECT @@innodb_buffer_pool_size/1024/1024/1024; +------------------------------------------+ | @@innodb_buffer_pool_size/1024/1024/1024 | +------------------------------------------+ | 10.000000000000 | +------------------------------------------+ 

innodb_buffer_pool_chunk_size  can be increased or decreased in 1MB (1048576 byte) units but can only be modified at startup, in a command line string or in a MySQL configuration file. 

Command line: 

shell> mysqld --innodb-buffer-pool-chunk-size=134217728 

Configuration file: 

[mysqld] innodb_buffer_pool_chunk_size=134217728 

The following conditions apply when altering innodb_buffer_pool_chunk_size : 

•If the new  innodb_buffer_pool_chunk_size  value * innodb_buffer_pool_instances is larger than the current buffer pool size when the buffer pool is initialized, innodb_buffer_pool_chunk_size  is truncated to innodb_buffer_pool_size  / innodb_buffer_pool_instances . 

For example, if the buffer pool is initialized with a size of 2GB  (2147483648 bytes), 4  buffer pool instances, and a chunk size of 1GB  (1073741824 bytes), chunk size is truncated to a value equal to innodb_buffer_pool_size  / innodb_buffer_pool_instances , as shown below: 

shell> mysqld --innodb-buffer-pool-size=2147483648 --innodb-buffer-pool-instances=4 --innodb-buffer-pool-chunk-size=1073741824; 

mysql> SELECT @@innodb_buffer_pool_size; +---------------------------+ | @@innodb_buffer_pool_size | +---------------------------+ | 2147483648 | +---------------------------+ mysql> SELECT @@innodb_buffer_pool_instances; +--------------------------------+ | @@innodb_buffer_pool_instances | +--------------------------------+ | 4 | +--------------------------------+ # Chunk size was set to 1GB (1073741824 bytes) on startup but was # truncated to innodb_buffer_pool_size / innodb_buffer_pool_instances 

