RAIN

(Redundant Array of Independent Nodes)

RAIN is a disk sub system that is used to obtain distributed data storage and security in network architecture by integrating management software and inexpensive hardware.

RAIN is designed with a view to achieve reliable and scalable network attached storage (NAS) by blending distributed computing and commodity hardware with effective management software. It aims at improvement of pitfalls of NAS systems that are non-redundant.

The concept of RAIN derived from redundant array of independent disks (RAID), which is similar system that is implemented at the disk level.

Redundant array of independent nodes may simultaneously be termed as redundant array of inexpensive nodes.

RAIN technology was designed as a research program jointly by Defense Advanced Research Project Agency and California Institute of Technology and NASA’s Jet Propulsion Laboratory.

RAIN technology is implemented as to increase fault tolerance in a cluster.

A centralized management interface is used to manage the storage clusters. A virtual pool of storage devices is created by the management software, which do not need network and storage administrators physically.

Any new RAIN node is automatically detected by the RAIN management software and all the nodes can communicate with each other.

If any of the nodes fail, the lost data is replicated among other nodes of RAIN architecture in a cluster to avoid immediate replacement of the failed nod.

Effective load balancing characteristics makes RAIN based grids more adaptable/resilient to application workload changes.

RAIN architecture provides high end solutions that reduces the number of nodes in the chain that links/connects the client and server, as well as to make the current node more autonomous and more robust.

The aim of RAIN technology is to design a system that is fault-tolerant, has high performance, and architecturally implements a portable clustering technology.

The RAIN technology aims to recognize and create key building blocks for distributed systems that are reliable, build using economically off-the-shelf components. RAIN technology also includes the new feature of re-establishing an out of order node with a new one and thus avoiding the break in information flow.

RAIN technology follows an open architecture approach to storage that implements inexpensive computing hardware in hand with a significantly smart management software to make it reliable and efficient.

The elements of RAIN configuration run in parallel with network protocols and operating system. The management software that is used provides the fault tolerance feature.

Advantages of RAIN

1. Fault tolerance - A RAIN cluster works as a true, distributed computing system that is susceptible to faults, it employs the principle of graceful degradation.
2. Simple to destroy and manage–RAIN technology deals with the issue of scalability on the layer where it is happening without the need to create additional layers in the front. The management software permits the user to monitor and configure the entire cluster by connecting to any of the nodes.
3. Open and portable –This technology is open and highly portable. It is compatible with a variety of hardware and software environment. Lately, it has been ported to Solaris, NT and Linux.
4. Support for heterogeneous environment – It supports a heterogeneous environment as well where the cluster can consists of nodes of different operating systems with different configurations.
5. No distance limitation –There is no distance restriction to RAIN technology. It allows clusters of geographically distributed nodes. It can work with many different Internet applications.
6. Availability – Another advantage of RAIN is its incessant availability. In case of Rainwall, it detects failures in software and hardware components in real time, shifting traffic from failing gateways to functioning ones without interrupting existing connections.
7. Scalability – RAIN technology is scalable. There is no limit on the size of RAIN cluster. Rainwall is scalable to any number of new Internet firewall gateways and allows the addition of new gateways into the cluster without service interruptions.
8. Load Balancing and Performance – New node can be added into the cluster on the spot to take part in load sharing, without detoriating the network performance as in case of Rainwall. Rainwall keeps track of the total traffic going into each node. When a disproportion is sensed, in the network traffic, it moves one or more of the virtual IPs on the more heavily-loaded node to the more lightly-loaded node. Any new nodes can be added into the cluster to participate in load sharing, without taking down the cluster.
9. Use of inexpensive nodes – RAIN uses loosely couples computing clusters using inexpensive hardware devices.  It uses management software that transmits tasks to various computers, and, in the event of a failure, will retry the task until a node responds. Many of the loosely coupled computing projects makes use of, to some degree, a RAIN strategy.

Ms. Priyanka Gupta

Assistant Professor

Dept. of Information Technology