Spectra Logic Spectra nTier300, Руководство по установке

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Glossary of Terms – U
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tiered storage Tiered storage is a data-storage environment consisting of two or more
kinds of storage. Different categories of data are assigned to different
types of storage media in order to reduce total storage cost. Categories
may be based on levels of protection needed, performance
requirements, frequency of use, and other considerations. Since
assigning data to particular media may be an ongoing and complex
activity, hierarchical storage management (HSM) software is often used
for automatically managing the process based on a company-defined
policy.
As an example of tiered storage, tier 1 data (such as mission-critical,
recently accessed, or top secret files) might be stored on RAID-protected
disk arrays connected directly to the host. Tier 2 data (such as financial,
seldom-used, or classified files) might be stored on less expensive disk
arrays on a storage area network (SAN). As the tier number increases,
less expensive, slower storage media can be used. Thus, tier 3 in a 3-tier
system might contain event-driven, rarely used, or archival data stored
on tape.
See also HSM .
U
USB
Universal serial bus. A plug-and-play hardware interface between a
computer and add-on devices (such as audio players, joysticks,
keyboards, telephones, scanners, and printers). With USB, a new device
can be added to a computer without having to add an adapter card or
even having to turn the computer off. USB’s hot-swap capability allows
devices to be plugged in and unplugged without turning off the system.
V
virtual disk
A virtual disk is a device that provides an area of usable storage capacity
on one or more physical disk drives. Virtual disks typically use RAID
technology to combine a group physical disk drives to create a large
logical disk. From the perspective of the hosts storing data on virtual
disk, it is simply a disk drive with very large capacity.
As with a physical disk drive, a virtual disk can be formatted to support
the file system requirements of various operating systems. Virtual disks
provide a means for allocating a portion of the storage system’s capacity
and performance to individual servers or applications.
volume
A logical structure defined over a set of drives (volume group) with a set
RAID level and capacity.