**8. Storage**

When processing a large amount of data, input data and results should be stored. Additionally, the performance of data intensive applications typically depends on the hardware and software infrastructure used for storage.

## **8.1 Classical storage**

In this type of storage, the primary and easiest way to store data is a simple hard drive attached directly to the node. This type of storage system is sometimes referred to as a direct storage (DAS). On these disks, data is stored using a classic hierarchical file system like ext3 or ReiserFS. These file systems are typically implemented by an operating system driver as a sensitive part for security, performance, and reliability. This type of storage allows for fast read and write operations since everything is done locally. It is also simple to use as it is used with any operating system. However, there is no easy way to exchange data between multiple nodes.

## **8.2 Centralized network storage**

A second way to store data is centralized network storage, usually referred to as etworkAttached Storage (NAS). In this case, a node has one or more disk connected and allows other nodes to read and write files through a standard interface and serve them through the network. Network File System (NFS) is primarily a protocol for accessing files over the network. While the server is free to implement any means of accessing the actual data to be provided over the network, most implementations simply depend on whether the data is directly accessible on the server. One of the main advantages of this type of architecture is the ease of sharing data between multiple compute nodes. Since the data is stored on a server, it is easily maintained.
