Optical jukebox
Encyclopedia
An optical jukebox is a robotic data storage device
Data storage device
thumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....

 that can automatically load and unload optical disc
Optical disc
In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces...

s, such as Compact Disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...

, DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

, Ultra Density Optical
Ultra Density Optical
Ultra Density Optical is an optical disc format designed for high-density storage of high-definition video and data.- Overview :...

 or Blu-ray disc
Blu-ray Disc
Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...

 and can provide terabyte
Terabyte
The terabyte is a multiple of the unit byte for digital information. The prefix tera means 1012 in the International System of Units , and therefore 1 terabyte is , or 1 trillion bytes, or 1000 gigabytes. 1 terabyte in binary prefixes is 0.9095 tebibytes, or 931.32 gibibytes...

s (TB) and petabyte
Petabyte
A petabyte is a unit of information equal to one quadrillion bytes, or 1000 terabytes. The unit symbol for the petabyte is PB...

s (PB) of tertiary storage. The devices are often called optical disk libraries, robotic drives, or autochangers. Jukebox devices may have up to 2,000 slots for disks, and usually have a picking device that traverses the slots and drives. The arrangement of the slots and picking devices affects performance, depending on the space between a disk and the picking device. Seek times and transfer rates vary depending upon the optical technology.

Jukeboxes are used in high-capacity archive storage environments such as imaging, medical, and video. Hierarchical storage management
Hierarchical storage management
Hierarchical storage management is a data storage technique which automatically moves data between high-cost and low-cost storage media. HSM systems exist because high-speed storage devices, such as hard disk drive arrays, are more expensive than slower devices, such as optical discs and magnetic...

 is a strategy that moves little-used or unused files from fast magnetic storage to optical jukebox devices in a process called migration. If the files are needed, they are migrated back to magnetic disk. Optical disc libraries are also useful for making backup
Backup
In information technology, a backup or the process of backing up is making copies of data which may be used to restore the original after a data loss event. The verb form is back up in two words, whereas the noun is backup....

s and in disaster recovery
Disaster recovery
Disaster recovery is the process, policies and procedures related to preparing for recovery or continuation of technology infrastructure critical to an organization after a natural or human-induced disaster. Disaster recovery is a subset of business continuity...

 situations. Today one of the most important uses for jukeboxes is to archive data. Archiving data is different from backups in that the data is stored on media that will last up to 100 years. The data is usually written on Write Once Read Many
Write Once Read Many
A Write Once Read Many or WORM drive is a data storage device where information, once written, cannot be modified. On ordinary data storage devices, the number of times data can be modified is not limited, except by the rated lifespan of the device, as modification involves physical changes that...

 (WORM) type discs so it can not be erased or changed.

Jukeboxes typically contain internal SCSI
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

 or SATA
Sata
Sata is a traditional dish from the Malaysian state of Terengganu, consisting of spiced fish meat wrapped in banana leaves and cooked on a grill.It is a type of Malaysian fish cake, or otak-otak...

 based recordable drives (CD-ROM, CD-R, DVD-ROM, DVD-R, DVD-RAM, UDO or Blu-ray) that connect directly to a file server and are managed by a third party jukebox management software. This software controls the movement of media within the jukebox, and the pre-mastering of data prior to the recording process.

Before the advent of the modern SAN
Storage area network
A storage area network is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices...

 and much cheaper hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...

s, large-volume storage on DVD was more price-efficient than magnetic media. Jukebox capacities have greatly increased with the release of the 50 gigabyte
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...

 (GB) dual layer Blu-ray (BD) format, with a road-map to increase to eight layers and 200 GB per disc. The current format, used in the DISC7000, allows 35 TB of storage from a single 700 disc jukebox. Optical disc libraries like the TeraStack Solution can store up to 78 TB of online
ONLINE
ONLINE is a magazine for information systems first published in 1977. The publisher Online, Inc. was founded the year before. In May 2002, Information Today, Inc. acquired the assets of Online Inc....

 and nearline data with a nominal power draw of 600 watts
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

. These two units show the wide variance of product attributes.

History

One of the first examples of an optical Jukebox was the unit designed and built at the Royal Aerospace Establishment at Farnborough, England. The unit had twin read/write heads, 12" WORM disks and the carousels were pneumatically
Pneumatics
Pneumatics is a branch of technology, which deals with the study and application of use of pressurized gas to effect mechanical motion.Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or compressed inert gases...

driven. It was produced to replace the 1/2 inch magnetic tape devices that were being used to store satellite data.

Special software drivers

Jukeboxes connect to a Windows, Unix, or other server using special software. The special software is not just a driver; it also includes a database that keeps track of the files on each of the discs. Users on the network can copy or drag and drop data to the server which automatically transfers the data to a CD, DVD, UDO or Blu-ray disc in the jukebox. The software also provides other functions including caching the data for both writing and retrieval functions, so as to improve performance.
Currently, jukeboxes are now known as libraries as the terminology has changed.
The jukebox hardware by itself is useless without software to comprehensively manage the appliance. Furthermore, speed and access time can be an issue if it is not properly configured.

Access time issues

All the jukeboxes work best when only a few users need to access the discs at the same time. Small jukeboxes have only one or two CD, DVD, UDO or Blu-ray drives, so only one or two users can share the jukebox at the same time. If additional users want to use a new disc, they have to wait for the disc to be swapped by the robotics in the jukebox. This takes from 4 to 9 seconds. Larger jukeboxes have six or more readers, so more users can simultaneously access the different discs at the same time.
A more efficient recommendation is to have a disk cache attached to the jukebox for a higher number of simultaneous users. This way, the configuration operates in a FILO (First In Last Out) Manner. Here, files accessed are only sent back to the optical discs after they have been utilized. Changes may or may not be saved or versioned based on the user configuration and accessibility settings on the storage management software that runs the optical jukebox.
The number of drives in the jukebox can be up to 6 depending on the size of the jukebox. The drives will read and write the data to the RAID / Disc cache and then present to end users. This way the 4 – 6 seconds read time only occurs during the initial data read process, then the data is sent to the cache.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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