This tutorial shows how you can enable networking in Xen guests (domU) on Hetzner's new EQ servers. With the new EQ servers, you can get up to three additional IPs that are in the same subnet as the server's main IP. The problem is that these additional IPs are bound to the MAC address of the host system (dom0) - Hetzner's routers will dump IP packets if they come from an unknown MAC address. This means we cannot use Xen's bridged mode, but must switch to Xen's routed mode where the host system (dom0) acts as the gateway for the guests.

Cherokee is a very fast, flexible and easy to configure Web Server. It supports the widespread technologies nowadays: FastCGI, SCGI, PHP, CGI, TLS and SSL encrypted connections, virtual hosts, authentication, on the fly encoding, load balancing, Apache compatible log files, and much more. This tutorial shows how you can install Cherokee on a Debian Lenny server with PHP5 support (through FastCGI) and MySQL support.

This tutorial shows how you can limit the CPU usage of a process with the tool cpulimit on Debian/Ubuntu. cpulimit is a simple program that attempts to limit the CPU usage of a process (expressed in percentage, not in cpu time). This is useful to control batch jobs, when you don't want them to eat too much CPU. It does not act on the nice value or other scheduling priority stuff, but on the real CPU usage. Also, it is able to adapt itself to the overall system load, dynamically and quickly.

This guide explains how to set up software RAID1 on an already running Debian Lenny system. The GRUB bootloader will be configured in such a way that the system will still be able to boot if one of the hard drives fails (no matter which one).

This document describes how to install a PureFTPd server that uses virtual users from a MySQL database instead of real system users. This is much more performant and allows to have thousands of ftp users on a single machine. In addition to that I will show the use of quota and upload/download bandwidth limits with this setup. Passwords will be stored encrypted as MD5 strings in the database.

This tutorial will explain you how to boot from a BTRFS filesystem with kernel 2.6.31-RC4 and BTRFS 0.19. BTRFS is a new filesystem with some really interesting features like online defragmenting and snapshots. BTRFS is an experimental filesystem, use at your own risk. The kernel used is also experimental.

FTP is a very insecure protocol because all passwords and all data are transferred in clear text. By using TLS, the whole communication can be encrypted, thus making FTP much more secure. This article explains how to set up ProFTPd with TLS on a Debian Lenny server.

This article explains how to set up a two-node load balancer in an active/passive configuration with HAProxy and heartbeat on Debian Lenny. The load balancer sits between the user and two (or more) backend Apache web servers that hold the same content. Not only does the load balancer distribute the requests to the two backend Apache servers, it also checks the health of the backend servers. If one of them is down, all requests will automatically be redirected to the remaining backend server. In addition to that, the two load balancer nodes monitor each other using heartbeat, and if the master fails, the slave becomes the master, which means the users will not notice any disruption of the service. HAProxy is session-aware, which means you can use it with any web application that makes use of sessions (such as forums, shopping carts, etc.).

This tutorial shows how to do data striping (segmentation of logically sequential data, such as a single file, so that segments can be assigned to multiple physical devices in a round-robin fashion and thus written concurrently) across four single storage servers (running Debian Lenny) with GlusterFS. The client system (Debian Lenny as well) will be able to access the storage as if it was a local filesystem. GlusterFS is a clustered file-system capable of scaling to several peta-bytes. It aggregates various storage bricks over Infiniband RDMA or TCP/IP interconnect into one large parallel network file system. Storage bricks can be made of any commodity hardware such as x86-64 servers with SATA-II RAID and Infiniband HBA.

This tutorial shows how to combine four single storage servers (running Debian Lenny) to a distributed replicated storage with GlusterFS. Nodes 1 and 2 (replication1) as well as 3 and 4 (replication2) will mirror each other, and replication1 and replication2 will be combined to one larger storage server (distribution). Basically, this is RAID10 over network. If you lose one server from replication1 and one from replication2, the distributed volume continues to work. The client system (Debian Lenny as well) will be able to access the storage as if it was a local filesystem. GlusterFS is a clustered file-system capable of scaling to several peta-bytes. It aggregates various storage bricks over Infiniband RDMA or TCP/IP interconnect into one large parallel network file system. Storage bricks can be made of any commodity hardware such as x86-64 servers with SATA-II RAID and Infiniband HBA.