Highly Available Servers

Introduction

ECMWF operates two separate clusters of highly available servers. A highly available server is designed so that there is no single point of failure within the system.

The HAPP cluster including the EVA 5000 Disk Subsystem

• HAPP - Data Acquisition, Preprocessing and Dissemination cluster
• HANFS - NFS fileserver cluster

The HAPP cluster consists of 4 HP rx4640 Integrity Servers, each with 4 1.5 GHz Itanium2 CPUs 4 GB of memory and 2 73 GB system disks. An HP EVA 5000 Fibre Channel disk subsystem connected to each server via HP Storageworks SAN FibreChannel switches. The disk subsystem provides about 3 TB of disk space. A seperate server with 2 Itanium2 CPUs is used for software development and testing.

The HP L-Class servers forming the HANFS cluster

The HANFS cluster consists of 2 HP L-Class servers, each with 2 PA-RISC 8500 CPUs and a HP EVA 3000 Fibre Channel disk subsystem accessible by each server. The EVA subsystem is connected to the 2 L-Class servers via 2 Fibre Channel switches.

All the systems in both clusters run HP-UX 11.0 . In order to provide high availability, both clusters use "ServiceGuard", a software package from HP. This allows services to be configured as packages. These can be moved from one system to another, if a system failure occurs, so that users will only notice a short interruption of a few minutes.