Toad

Toad (toad.stack.nl) is one of Stack's fastest servers. It is one of the login servers that all members have accounts on. It is also the primary Stack webserver (running www.stack.nl and several other sites) and runs several other services.

Hardware

Toad is running on four Opteron cores at 1.8GHz, with two cores per package. The main board is a Tyan Thunder K8SR, and is equipped with 4 GB of registered ECC main memory. The local system installed on two 36GB 10000 RPM U320 SCSI drives in a RAID1 mirror. The case is a 3U Procase rackmount system with redundant power supplies. Each power supply is connected to a different UPS, in turn connected to different power groups for maximum resiliency. The system is connected to our Cybex XP4040 KVM system, and has a serial console connected to one of our terminal servers.

Operating system

Like most Stack servers, toad runs a version of the FreeBSD operating system. Currently FreeBSD 7.0 is installed. Toad runs a 64-bit version of FreeBSD, but has (limited) compatibility for 32-bit binaries.

Jails

The performance of toad makes it a good candidate to run a number of additional, "virtual" FreeBSD installations on it for particular services. These are not actual virtual machines, but partitioned areas within the FreeBSD operating system, called "jails". Jails make it possible to run certain applications in a separate environment, which provides security through isolation. This is however not our primary reason to use jails. Many applications require large amount of support libraries, and mixing up many applications can lead to an unmanageable amount of software packages, dependencies and associated conflicts. Isolation into jails allows for easy management of the applications and their software dependencies.

Toad is currently running three jails, each named wjX, where X is a number and "wj" stands for "web service jail". The following jails are in operation:

• wj0: This is a jail running Apache/PHP, and is used for our webmail applications (Horde/IMP and SquirrelMail); it is also used for the database administration site and runs some HTTP download mirrors (which require high throughput).
• wj3: This jail runs the Stack Subversion (SVN) service, running on top of Apache.
• wj4: This is another Apache/PHP jail, used for development and testing of web applications.