With the electronic storage technology is a separation between the management and control software is on the one hand and the actual storage media on the other. Conventional magnetic storage media in the past were regarded as not suitable for the audit of electronic archiving, because the stored information can be changed at any time and overwritten. This applies particularly true hard drives that are dynamically managed by operating systems. Magnetic influences, "head crashes" and other risks pointed the disks to the role of pure online store. When magnetic tape was added in addition to the eras ability that these media are subject to high loads and wear, as well as the magnetic layers while excessively long storage. Conventional WORM media
In the 80 years special digital optical storage media have been developed that can non-contact in their drive with a laser is described only once. This memory technology known as WORM "Write Once, Read Multiple Times. The media themselves are protected by their physical properties to change and offer a substantial longer life than the previously known magnetic media.
In this category fall the following types of storage media:
CD-WORM
CD-R media
When only once recordable compact disc with about 650 megabytes of memory, the memory interface of the medium is irreversibly altered when writing. CD media are standardized by ISO 9660 and inexpensively. The quality of some cheaper media, but consider for a long-term archiving as not sufficient. For drives and media, there are numerous providers. The control of the drives is directly supported by the operating systems.
DVD-WORM
Similar to the CD in the DVD-WORM storage, the surface irreversibly changed in the medium. DVDs are not yet uniformly standardized and offer different storage capacity 4 to 17 GigaByte. When used for archiving is therefore important to ensure that the drive and media to meet requirements of the long-term availability. There are also many vendors and most drives are directly supported by the popular operating systems.
5 ¼ "WORM
These media and drives is the traditional technology that was developed specifically for electronic archiving. The media are in a protective case and are therefore better protected against environmental influences as CD and DVD that were developed for the consumer market. The media will be described with a laser, providing exceptional image distortion security. The current state of the art are so-called UDO media, which use a blue laser and offer a storage capacity of 50 gigabytes. In the future, is still significantly higher capacities expected each medium. The disadvantage is that previous generations of media each of the 5 ¼-media in new drives can not be used. For the connection of 5 ¼ "drives, special driver software is necessary.
For the management and use of the media known as jukeboxes, so plate-changing machines are in use. This software-ready to provide the required information by the media. The software makes it usually also manage those media that are no longer in the jukebox and must be manually fed on demand. The software for controlling jukeboxes will be directly integrated into the archiving software, as well as independent control software available. For the connection of jukeboxes, use is usually their own server to take over the management and caching. Meanwhile, such systems can also as a NAS Network Attached Storage, or be used integrated with SAN Storage Area Networks.
Newer technologies
In addition to the traditional archive storage based on rotating, digital-optical removable media, now take two additional technologies Content Addressed Storage (CAS)
This is hard to systems that reach through special software, the same characteristics as a traditional WORM medium. Overwriting or modifying the information stored on the memory system is prevented by the coding in the storage and the specific address. These CAS storage systems are closed subsystems, which can, however, almost as conventional hard disk systems directly into the IT environment to be integrated. They offer storage capacity with high performance in the TB area.
WORM tapes
WORM tapes are magnetic tapes that meet several requirements for the combined properties are also a traditional WORM medium. These include special and protected cassette tape media and special drives to ensure . Especially in data centers, where robots and tape library systems are already in place, put the WORM tapes both easy to integrate component for long-term archiving . The existing control software can deal with the media and automate appropriate copying and backup. Especially for larger businesses and government data centers with disk or WORM tape libraries make-an option that they integrate easily into normal operations can be.
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