Troubleshooting

A quick reference for checking listening ports on Linux using netstat and ss, including the flags that matter and what each output column means.

A practical walkthrough of Nginx’s limit_req module, showing how to cap request rates and protect PHP endpoints from HTTP-based denial-of-service attacks.

Nginx status code 444 silently drops a connection without sending any HTTP response to the client. Learn when and how to use it for security and traffic management.

A deep dive into why MySQL on NUMA systems suffers from unpredictable swapping, and how a single numactl interleave fix eliminates the problem entirely.

Percona XtraDB Cluster can recover a crashed node and rejoin it to the cluster using an incremental state transfer. This post walks through how GTID-based position recovery works under the hood and what you will see in the error log during the process.

A quick reference for understanding the key qualifiers that appear in RAID controller error codes, so you can pinpoint the exact failure condition instead of guessing from a generic error message.