Server tuning

MySQL 8.4 LTS and 9.x: what WordPress developers need to know MySQL changed its release model: since 2023 there are Long-Term Support releases (8.4, released in April 2024) for production, and Innovation releases (9.0, 9.1 and so on, roughly every quarter) with new features, each supported only until the next one. At the same time…

MySQL 8.4 LTS and 9.x for WordPress hosts: what changes, what to wait for MySQL changed its release model in 2024: Long-Term Support releases (8.4, released April 2024) for production, and Innovation releases (9.0, 9.1, …) every few months with new features and a short support window. MySQL 8.0 reached its end of life in…

MySQL replication with GTID for WordPress: set up, monitor, fail over A replica of the WordPress database gives a second copy that is seconds behind, a place to run heavy reports and backups without touching the primary, and a server to switch to when the primary fails. GTID-based replication (global transaction identifiers) makes the last…

Limit PHP-FPM, cron and imports with systemd slices and cgroups v2 On a server that runs several WordPress sites, one site’s runaway import or a crawler storm on another can take all CPU and memory, and every site becomes slow. Linux cgroups v2 can cap a group of processes, and systemd exposes them through simple…

sysctl and TCP settings for a busy WordPress server: what actually matters Lists of “kernel tuning for high traffic” circulate with dozens of sysctl values, most of them copied from servers with very different workloads. On a WordPress server, the limits that are reached in practice are few: the connection backlog when a traffic spike…

The Linux OOM killer and swap on a WordPress server When a Linux server runs out of memory, the kernel’s out-of-memory killer picks a process and kills it. On a WordPress server, the process with the most memory is usually MySQL, so the site goes down with “Error establishing a database connection”, although the real…

InnoDB buffer pool for WordPress: size it, then check that it works The InnoDB buffer pool is MySQL’s memory cache for table and index pages. When the working set of a WordPress database (the posts, the meta, the options, the WooCommerce lookup tables that are actually read) fits into it, queries are served from RAM.…

“Too many connections”: PHP-FPM, MySQL and when ProxySQL helps PHP has no connection pool in the usual sense: every request that WordPress handles opens its own MySQL connection and closes it at the end. Under load, the number of connections equals the number of busy PHP-FPM workers, from every web server. When that number exceeds…

Log rotation for WordPress, Nginx and PHP-FPM with logrotate and journald Logs grow quietly. A busy site writes hundreds of megabytes of Nginx access log per week, a plugin with a notice in a loop fills debug.log with gigabytes, and one day the disk is full and MySQL stops. Two tools keep logs in check…