Converged storage

Scale-out architecture is a component of converged storage. Scale-out storage is the combination of modular computers and standardized storage components to create federated storage pools.^[18] The result is an increase of computer power, bandwidth and storage capacity that can exceed that of a single traditional storage array or high performance computer.^[19] Storage vendors such as NetApp, Dell, Hewlett-Packard and EMC provide scale-out storage to address both the growth of unstructured data and the need to simplify data center operations.^[20] At the file system level, parallel file systems like BeeGFS are available to provide a single namespace with automatic data distribution for shared network access across the internal storage devices of multiple servers.

Scale-out storage differs from scale-up architectures in traditional storage, which primarily scales by adding many individual disk drives to a single non-clustered storage controller.^[21] In a scale-out architecture, management software is used to manage the multiple storage devices, to act like a single system.^[22] Storage analyst company, Enterprise Strategy Group, writes that scale-out storage can help to provide timely IT provisioning, improve system availability and provide better resource utilization.^[23]

Storage federation (also known as federated storage) uses distributed volume management to shift workloads from busy arrays to those with available capacity. This is done using native peer-to-peer communication.^[24] Multiple autonomous storage systems are combined and managed as a single storage pool.^[25] This helps to improve storage utilization, balance workloads and ease storage migration.

Converged storage supports the multitenant (multitenancy) architecture of cloud computing, in which multiple machines or users access the virtual and physical resources at the same time. In addition to storage, the other resources accessed in this architecture are processors and networks.^[26] A converged storage does this by moving application workloads between disk systems.^[27]

Monolithic storage architectures share RAM across multiple IO controllers. They have been characterized as large storage arrays that require a large upfront investment and resources. Hitachi Vantara, is quoted as saying such storage requires enterprises to spend $500,000 on customizing their data centers to support the power requirements of monolithic equipment.^[28] Monolithic arrays provide failover benefits. The shared cache architecture of monolithic arrays ensures that if one cache module fails, another cache is used to process the user's request. However once you have more than a single system this architecture is complex and requires investment to manage and control the interactions between the different components.^[29] Monolithic architectures support both block and file-based architectures, either independently or in a unified storage system that brings together both block and file.^[30]

Direct-attached storage (DAS) provides scaling of storage directly attached to the server. The storage is dedicated to a single server and is not sharable among multiple servers. Data stored on a Storage area network (SAN) and network-attached storage (NAS) architectures can be shared among several server applications.^[31]