The innodb_buffer_pool_size is just one memory setting of many. MariaDB will allocate additional memory for other things.

Here's a good place to start…

https://mariadb.com/kb/en/mariadb-memory-allocation/

From: Maria-discuss <maria-discuss-bounces+rhys.campbell=swisscom.com@lists.launchpad.net> On Behalf Of ragul rangarajan
Sent: 09 November 2021 15:34
To: maria-discuss@lists.launchpad.net
Subject: [Maria-discuss] Clarification on Memory utilization of Mariadb

Hi Team,

Need clarification on Memory utilization of Mariadb.

I have a java application with MariaDB that runs on the same Rhel 7 server with physical memory(RAM) allocated as 12GB where I would see the normal utilization at the start as below.

sys> free -h

              total        used        free      shared  buff/cache   available

Mem:            11G        7.8G        1.6G        9.0M        2.2G        3.5G

Swap:            0B          0B          0B

Over a period of time say >6month, I could see the RAM utilization is almost full, and available space is very less but still, the application continues to work fine without any issues.

sys> free -h

              total        used        free      shared  buff/cache   available

Mem:            11G         11G        134M         17M        411M        240M

Swap:            0B          0B          0B

I don't see any OOM issue or high usage of RSS at the java application level but I could see MariaDB occupies huge memory.... apart from that overall application runs fine.

To ensure this we observed memory utilization at the large-scale application servers where we deployed MariaDB and Java applications into different servers with 128GB each and could observe that the system with MariaDB uses full RAM size whereas the Java application consumption looks stable.

Server with Java application

sys> free

              total        used        free      shared  buff/cache   available

Mem:         128755      125171         606         118        2977        2694

Swap:         65535        9746       55789

Server with MariaDB

sys> free

              total        used        free      shared  buff/cache   available

Mem:         128755      125171         606         118        2977        2694

Swap:         65535        9746       55789

MariaDb conf:

innodb_buffer_pool_size=102G
innodb_buffer_pool_instances=8
innodb_io_capacity=3000
innodb_log_buffer_size=8M
innodb_log_file_size=2047MB
innodb_log_files_in_group=2

Is this expected that MariaDB consumes overall memory and manages within RAM size.... regardless of buffer size configured? 

Do we need to optimize any configuration to control the MariaDB consumption apart from buffer pool size?

Thanks and Regards,

Ragul