Hi Catal From experience, in most cases where a mariadb server uses more memory than expected, especially if it’s consistently growing to the point of oomkiller taking it out, the culprit has been the default malloc handler on the OS. I’ve found this both on various flavours of EL (Centos and Rocky, 6-9) as well as Debian 12. As it’s a bit of a FAQ, I jotted down how we solve it by using jemalloc or tcmalloc, both of which work well with MariaDb on linux. https://digdilem.org/2025/03/solving-excess-memory-usage-in-mariadb/ I would suggest trying that before going further. It’s a quick and cheap fix, and if it doesn’t work, easy to revert. Regards, Simon See below: Operating system: "Debian 12.10 (bookworm)" MariaDB Version: 10.11.11-MariaDB-0+deb12u1-log The server was configured (limited) to use for InnoDB -> max 3GB Ram MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE 'innodb_buffer_pool_size'; +-------------------------+------------+ | Variable_name | Value | +-------------------------+------------+ | innodb_buffer_pool_size | 3221225472 | +-------------------------+------------+ 1 row in set (0.001 sec) But, on that server we are running also MySam, Memory and Innodb, in total, ~70 databases (8 MySam, 1 MEMORY, and the rest are InnoDB) MariaDB [mysql]> select count(distinct db) from db; +--------------------+ | count(distinct db) | +--------------------+ | 73 | +--------------------+ 1 row in set (0.001 sec) MariaDB [mysql]> SYSTEM 4CPU, 7.8GB RAM root@adsns-db-node0:~# df -h Filesystem Size Used Avail Use% Mounted on udev 3.8G 0 3.8G 0% /dev tmpfs 776M 764K 775M 1% /run /dev/sda1 150G 48G 97G 34% / tmpfs 3.8G 0 3.8G 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock /dev/sda15 241M 138K 241M 1% /boot/efi tmpfs 776M 0 776M 0% /run/user/0 root@adsns-db-node0:~# I found some articles on internet regarding /dev/shm, which could influence mysql performance. In my case /dev/shm is not used even defined, so the system could use the whole available RAM - 7.8GB RAM, so I excluded this as possible cause. MariaDB [(none)]> SHOW VARIABLES LIKE '%buffer_size%'; +----------------------------+-----------+ | Variable_name | Value | +----------------------------+-----------+ | aria_pagecache_buffer_size | 134217728 | | aria_sort_buffer_size | 268434432 | | bulk_insert_buffer_size | 8388608 | | innodb_log_buffer_size | 16777216 | | innodb_sort_buffer_size | 1048576 | | join_buffer_size | 4194304 | | key_buffer_size | 10485760 | | mrr_buffer_size | 262144 | | myisam_sort_buffer_size | 134216704 | | preload_buffer_size | 32768 | | read_buffer_size | 131072 | | read_rnd_buffer_size | 262144 | | sort_buffer_size | 2097152 | +----------------------------+-----------+ 13 rows in set (0.001 sec) Traffic is not high, just 123 queries per second. MariaDB [(none)]> status; -------------- mysql Ver 15.1 Distrib 10.11.11-MariaDB, for debian-linux-gnu (x86_64) using EditLine wrapper Connection id: 877596 Current database: Current user: root@localhost SSL: Not in use Current pager: stdout Using outfile: '' Using delimiter: ; Server: MariaDB Server version: 10.11.11-MariaDB-0+deb12u1-log Debian 12 Protocol version: 10 Connection: Localhost via UNIX socket Server characterset: utf8mb4 Db characterset: utf8mb4 Client characterset: utf8mb3 Conn. characterset: utf8mb3 UNIX socket: /run/mysqld/mysqld.sock Uptime: 7 days 3 hours 24 min 6 sec Threads: 78 Questions: 75901186 Slow queries: 4891595 Opens: 12573592 Open tables: 2000 Queries per second avg: 123.007 -------------- MariaDB [(none)]> Even I am restarting mariadb, after a short time, the memory usage is 85% root@adsns-db-node0:~# free -g total used free shared buff/cache available Mem: 7 6 0 0 0 1 Swap: 0 0 0 root@adsns-db-node0:~# The swap is not used, just the memory, which is ok. CPU usage is less than ~10%, so is ok. See below, output of top. %Cpu(s): 2.2 us, 0.7 sy, 0.0 ni, 96.2 id, 0.4 wa, 0.0 hi, 0.4 si, 0.0 st MiB Mem : 7750.8 total, 161.4 free, 6351.8 used, 712.6 buff/cache MiB Swap: 0.0 total, 0.0 free, 0.0 used. 1399.0 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1555028 mysql 20 0 7752424 6.5g 15476 S 10.6 85.2 188:29.16 mariadbd root@adsns-db-node0:~# pstree |grep maria |-mariadbd---51*[{mariadbd}] root@adsns-db-node0:~# All 51 childs of mariadb are using 85% from the system memory (each child ~1.6% of total RAM). I found a mysql calculator and changing innodb_buffer_pool_size - its default value 8M - with 3G, I got ~3.7GB ... still not 6.6G (aprox 85% from total RAM). See: https://www.mysqlcalculator.com/ 5. Why this difference, from 3.7GB up to 6.6GB? 6. Where could it be the rest of 2GB which is used by mariadb (from 3.7GB up to 6.6GB)? Any help will be appreciated. Catal From: cata via discuss <discuss@lists.mariadb.org> Sent: 02 April 2025 15:27 To: discuss@lists.mariadb.org Subject: [MariaDB discuss] it is normal to have a memory usage of 85%? Hi everybody, I am new here and I am confronted with a situation, so I will start with the questions first: 1. It is normal that on my server, mariadb to use almost 85% of available ram or something is wrong? 2. In case I want to limit the whole application (mariadb) to not use more than 5.5 GB RAM from total of 7.8GB it could be possible - without affecting it's performance? 3. Is anything to optimize (change) now? If yes, which variable? 4. Do we need more RAM for this server or actual RAM could be enough?