Diskless Shared Root Cluster
Encyclopedia
A diskless shared-root cluster is a way to manage several machines at the same time. Instead of each having its own operating system
(OS) on its local disk, there is only one image of the OS available on a server, and all the nodes use the same image. (SSI cluster = single-system image
)
The simplest way to achieve this is to use a NFS server, configured to host the generic boot image for the SSI cluster nodes. (pxe + dhcp + tftp + nfs)
To ensure that there is no single point of failure
, the NFS export for the boot-image should be hosted on a two node cluster.
The architecture of a diskless computer cluster makes it possible to separate servers and storage array. The operating system as well as the actual reference data (userfiles, databases or websites) are stored competitively on the attached storage system in a centralized manner. Any server that acts as a cluster node can be easily exchanged by demand.
The additional abstraction layer between storage system and computing power eases the scale out of the infrastructure. Most notably the storage capacity, the computing power and the network bandwidth can be scaled independent from one another.
A similar technology can be found in the TruCluster
(Tru64-UNIX) in the Unix
sector.
The open-source implementation of a diskless shared-root cluster is known as Open-Sharedroot
.
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
(OS) on its local disk, there is only one image of the OS available on a server, and all the nodes use the same image. (SSI cluster = single-system image
Single-system image
In distributed computing, a single system image cluster is a cluster of machines that appears to be one single system. The concept is often considered synonymous with that of a distributed operating system, but a single image may be presented for more limited purposes, just job scheduling for...
)
The simplest way to achieve this is to use a NFS server, configured to host the generic boot image for the SSI cluster nodes. (pxe + dhcp + tftp + nfs)
To ensure that there is no single point of failure
Single point of failure
A single point of failure is a part of a system that, if it fails, will stop the entire system from working. They are undesirable in any system with a goal of high availability or reliability, be it a business practice, software application, or other industrial system.-Overview:Systems can be made...
, the NFS export for the boot-image should be hosted on a two node cluster.
The architecture of a diskless computer cluster makes it possible to separate servers and storage array. The operating system as well as the actual reference data (userfiles, databases or websites) are stored competitively on the attached storage system in a centralized manner. Any server that acts as a cluster node can be easily exchanged by demand.
The additional abstraction layer between storage system and computing power eases the scale out of the infrastructure. Most notably the storage capacity, the computing power and the network bandwidth can be scaled independent from one another.
A similar technology can be found in the TruCluster
TruCluster
TruCluster is a closed-source high-availability clustering solution for the Tru64 UNIX operating system. It was originally developed by Digital Equipment Corporation , but was transferred to Compaq in 1998 when Digital was acquired by the company, which then later merged with Hewlett-Packard ....
(Tru64-UNIX) in the Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
sector.
The open-source implementation of a diskless shared-root cluster is known as Open-Sharedroot
Open-Sharedroot
Open-Sharedroot is a single-system image clustering solution for Linux.The Open-Sharedroot Project is based on a clustered filesystem like the Red Hat Global File System or Oracle Cluster Filesystem 2 to build a Shared Root Cluster....
.
Literature
- Marc Grimme, Mark Hlawatschek, Thomas Merz: http://www.redhat.com/magazine/021jul06/features/gfs_update Data sharing with a Red Hat GFS storage cluster
- Marc Grimme, Mark Hlawatschek http://www.atix.de/downloads/shared-root-cluster.pdf German Whitepaper: Der Diskless Shared-root Cluster (PDF-Datei; 1,1 MB)
- Kenneth W. Preslan: http://www.redhat.com/docs/manuals/csgfs/admin-guide/ Red Hat GFS 6.1 – Administrator’s Guide
External links
- http://www.open-sharedroot.org/ – The homepage of Open-Sharedroot
- http://sourceforge.net/projects/open-sharedroot/ – The project page of Open-Sharedroot
- http://w3.biff.ch/node/465/ – Tutorial how to implement Open-Sharedroot
- http://www.open-sharedroot.org/documentation/demo-cluster – Ready-to-run cluster within a VMware environment