MySQL Bugs: #58332: Multiple buffer pool instances, only one is shown

Bug #58332	Multiple buffer pool instances, only one is shown
Submitted:	19 Nov 2010 17:59	Modified:	10 Feb 2011 23:34
Reporter:	Nicklas Westerlund (OCA)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Enterprise Monitor: Web	Severity:	S3 (Non-critical)
Version:	2.3	OS:	Any
Assigned to:	Mark Leith	CPU Architecture:	Any

Description:
When monitoring a 5.5 instance that is used in testing, and having enabled innodb_buffer_pool_instances to be >1, we still only get one graph for buffer pool info in MEM, which obviously only has only a subset of the total size

How to repeat:
set innodb_buffer_pool_instances > 1 and restart mysql, then check your graphs

Suggested fix:
monitor each instance independent of eachother, or perhaps also provide an aggregate

Hi Nicklas,

What do you have the "innodb_buffer_pool_size" set to? The variable "innodb_buffer_pool_instances" in 5.5.x essentially partitions the buffer pool into "innodb_buffer_pool_instances" equally-sized segments that take up "innodb_buffer_pool_size" memory. If your graph shows ""innodb_buffer_pool_size", then this is working as expected.

Mark, 

I'm using advisor version 2.3.0.2036.

Just as a test I set the instances to be 10 and total buffer pool size to 1G. The graphs show ~100M (102 or so) as 'total size'.

Verified as described

http://bugs.mysql.com/bug.php?id=58461 is opened to track InnoDB changes.

Gary Whizin writes: 
This is an issue with the innodb plugin in 5.1 as well and will go away when #58461 is fixed by the innodb team. Meanwhile, we'll add a note to the MEM readme to alert MEM users to this problem.

Bill Weber writes: 
verified showing the correct total buffer size with build 2.3.2.2053

Added to 2.3.2 change log:

The graph for the InnoDB buffer pool now reports correct totals when
innodb_buffer_pool_instances is set to a value greater than 0.

Bug #60418 was marked as a duplicate of this one.