Google doesn’t reveal exactly how many servers it has, but I’d estimate it’s easily in the hundreds of thousands.
Linux Commodity computing is computing done on commodity computers as opposed to supermicrocomputers or boutique computers. Commodity computers are computer systems manufactured by multiple vendors, incorporating components based on open standards.
M. Shuaib Khan has published a list of open-source cluster management systems.
Personally, I had used openMosix and Red Hat Cluster software (which is also based upon open source software funded by Red Hat).
From the article: In computing world, the term “cluster” refers to a group of independent computers combined through software and networking, which is often used to run highly compute-intensive jobs. With a cluster, you can build a high-speed supercomputer out of hundreds or even thousands of relatively low-speed systems. Cluster management software offers an easy-to-use interface for managing clusters, and automates the process of queuing jobs, matching the requirements of a job and the resources available to the cluster, and migrating jobs across the cluster:
Read this article it offers feature, cons and pros of each solution.
If you try to mount an ext3 Linux filesystem on a SAN from multiple nodes at the same time you will be in serious deep trouble.
SAN based storage allows multiple nodes to connect to same devices at the same time. Ext3/2 are not cluster aware file system. They can lead to a disaster such as kernel panic, server hang, corruption etc.
You need to use something which supports:
- Useful in clusters for moderate scale out and shared SAN volumes
- Symmetrical Parallel Cluster File System, Journaled
- POSIX access controls
Both GFS (RedHat Global File System) and Lustre (a scalable, secure, robust, highly available cluster file system) can be used with SAN based storage allows multiple nodes to connect to same devices at the same time.
Many newbie get confused as Linux offers a number of file systems. This paper (Linux File System Primer) discusses these file systems, why there are so many, and which ones are the best to use for which workloads and data.