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storage virtualization

Storage virtualization is a collective term for various software and hardware techniques with which storage space or storage components are made available to the user in a logical form. In accordance with the principles of virtualization, resources are either divided up - as in the case of the partitions of a hard disk, for example - or combined, as is the case with volume managers, which provide logical drives that can span several hard disks.

Storage area networks( SAN) combine multiple storage subsystems into a continuous and unified storage view that can be used like one large storage, e.g., in an enterprise-wide IT environment.

Flexibility through storage virtualization

Storage virtualization adds a logical - virtual - layer to the storage environment, decoupling the user from physical constraints so that resources can be partitioned or pooled away from the limits imposed by hardware constraints. Storage virtualization provides the user with more flexibility, it facilitates maintenance - e.g. removal of a hard disk from a RAID system without loss of data or interruption of operation, it simplifies backups and data migration, it offers better utilization of storage space, regulation of access rights as well as organization of the storage environment, which by means of virtualization can be oriented according to content aspects instead of purely technical conditions. For example, virtualization allows storage systems to be transparently added or removed from a storage network without affecting the user or an application.

By hiding the complexity of the technical storage infrastructure from users, applications and administrators, virtualization greatly simplifies both use and management. This is especially true for very large storage environments such as SANs: these often grow historically over the years, creating a heterogeneous infrastructure. With suitable storage virtualization techniques, e.g. through special controllers, consolidation can be realized by integrating all components and subsystems into one - virtually homogeneous - large storage system. Moreover, this is often the only economical way to resolve interoperability problems between systems from different manufacturers.

Implementation techniques

Storage virtualization

Storage virtualization

Due to the complexity of storage systems and their usage, storage virtualization techniques are implemented at different levels and with a wide variety of techniques. A small selection: Host-based as a function of the operating system, e.g. as a file system or logical volume manager; implemented in the storage device, e.g. as a RAID controller; network-based, e.g. as a Fibre Channel protocol with a mix of hardware and software techniques for networking storage subsystems. With SANs, a distinction is usually made between three approaches, depending on where the virtualization layer is placed: integrated into the SAN within dedicated virtualization servers(in-band approach), decoupled from the storage data stream in the LAN (out-of-band) or within intelligent switches.

Informations:
Englisch: storage virtualization
Updated at: 09.11.2013
#Words: 452
Links: software (SW), hardware (HW), space (SP), user, indium (In)
Translations: DE
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