Insights, tutorials, and updates from the CoolVDS team
Build an OpenVPN 2.2 gateway on CentOS 6 with a private CA, and fix the usual failures: missing TUN device, no forwarding or NAT, and iptables rule order.
How to confirm that MySQL 5.5 is stuck on disk I/O, and how to tune the I/O scheduler, ext4 mount options and InnoDB settings for flash or fast virtual storage.
How to run a private, key-only Git server with Gitolite 2.x on CentOS 6, with access rules kept in a Git repository. Covers latency, I/O, and backups.
Cut disk waits on a MySQL 5.5 server on CentOS 6: convert tables to InnoDB, size the buffer pool and logs, set the flush policy, I/O scheduler and swappiness.
Why asynchronous replication can lose committed transactions, and how MySQL 5.5 semisync and PostgreSQL 9.1 synchronous replication address it on a CentOS 6…
A 2010-era baseline for CentOS 5 and Ubuntu 10.04: key-only SSH, a default-drop iptables policy, sysctl network settings and fewer listening services.
Why plain FTP exposes credentials, and how to lock users into a directory with OpenSSH ChrootDirectory and internal-sftp on CentOS 5.
Why Apache prefork wastes RAM on static files and slow clients, and how a lighttpd front end plus tuned MaxClients and keep-alive fixes it on CentOS 5.
A 2009 reference for VPS users on container-based hosting: why "Cannot allocate memory" appears while free shows RAM, and how to read and fix it.
A 2009 reference for choosing between a VPS and a dedicated server. It covers how to find and fix OpenVZ memory-limit failures with user_beancounters.
Why services in an OpenVZ container fail with allocation errors while free memory looks fine, and how to find and raise the exhausted User Beancounter limit.
How to remove the single points of failure from a small web cluster in 2009: two HAProxy nodes sharing a VRRP address in front of two or more web nodes.