Apple last week launched a clustering option for its Xserve servers that gives users higher availability and reliability, as well as enhanced options for running the servers in high-performance computational clusters and server farms.The company has found that its Xserve fits as well into computational clusters as it does into workgroups and departments within educational and graphics organizations.The Cluster Node option consists of what Apple calls a head node and compute node. The head node uses a dual 133-GHz PowerPC G4 server with 2G bytes of memory and one 60G-byte drive for booting. As many as three 180G-byte drives need to be available for striping data and file sharing via the Network File System. The compute node consists of a dual-processor Xserve with 1G byte of memory and a 60G-byte drive for booting. Users can add an Asante Gigabit Ethernet switch.Scientific and technical applications can take advantage of as much as 800 gigaflops of performance in a standard rack configuration. This performance is made possible by the 128-bit vector-processing unit in the PowerPC G4 chip.David Bratt, technology architect for H. Lee Moffitt Cancer Center in Tampa, Fla., uses some of these applications."The deployment of Mac OS X is the primary reason for the sudden attraction of Macs at our organization," says Bratt. "The researchers with Unix workstations like it because it is basically FreeBSD with a [Windows-like graphical] interface. Now that we have the quasi-Unix look and feel with Mac OS X, we have several options for managing Macs."Bratt says Macs are being installed more often in Moffitt's research division, where they are used for computationally intense bioinformatic applications that are often written for Linux or Macintosh servers and workstations.A popular application for Xserve clusters is Basic Local Alignment Search Tool (BLAST), which Apple claims consumes as much as 70% of compute time in biotechnology applications. BLAST searches require both processing power and memory bandwidth. A test Apple conducted showed that the PowerPC G4 was as much as five times faster than an IBM xSeries 335 and a Sun LX50 Server executing a BLAST search.A feature in Mac OS X Server called NetBoot lets administrators create disk images for servers and deploy them across the cluster. NetBoot lets multiple servers or cluster nodes be managed as if they were a single server. Additionally, in the event of failure, a server can use the NetBoot function to boot from the network.Mac OS X Server also is an advantage in scientific and technical environments where admins are familiar with Unix utilities, commands and scripting languages. OS X Server contains a command-line compiler and developer tools for porting command-line applications to Mac OS X and OS X Server.The Cluster Node option will be available in a 10-node pack next month for $2,800.