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Computing Report – Storage Media

Magnetic Tapes

Tape Drives

Tape drives have been successfully used as a backing storage medium for many years now, with storage capacity increasing as technology is improved. It is often used as the preferred backup method for servers and small companies.

Advantages are:

  • It is often useful for people who create a large amount of data to back up weekly or monthly. With tape drives, this can be done without the need for multiple hard drives. Infrequently used data can be archived to tapes, which can also be accessed off site.
  • Tape drives are used when high reliability and relatively high capacity is needed. For example, some have a MTBF (Mean time between failures) of one million hours when used for 20% of the day, or many hundred thousand hours used constantly.
  • Tape drives can be expensive initially, but become extremely inexpensive when you factor in the low cost of the media over time.

Disadvantages are:

  • Tape backups store and retrieve data sequentially. The last file backed up can't be accessed until the rest of the tape is read; other types of backup storage (for example: Hard Disk Drives) use random access, which enables any file on the device to be located and used in mere seconds.
  • Whenever multiple tapes or disks must be used to make a backup, the chances of backup failure increase. Disks also have to be loaded manually, or using an autoloader. This may sometimes rule out the possibility of backing up overnight, etc.
  • Writing data to tape drives is generally quite slow, with about 30 GB of data taking a few hours. Even with faster tape drives, there are problems: They often have minimum data transfer rates, because if they went slower than their rated minimum, they wouldn't record a good quality signal and would lose data. If a tape drive with a 50MB/sec (mega bytes per second) write speed is fed a data stream at only 25MB/s, it fills up a buffer memory and then writes at 50MB/s for a few seconds, rewinds and then writes at 50MB/s again. This can in effect lead to the actually writing speed to be much lower than stated.
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DAT (Digital Audio Tape) Drives

This type of storage was invented by Sony for music storage use, but it is now often used as backing storage. It uses DDS (Digital Data Storage) technology to store up to 160GB of data with DDS-5.

Advantages are that:

  • It uses USB (Universal Serial Bus) technology for universal ‘plug and play’ connectivity.
  • The low cost means that it is usually less expensive than tape drives for home users and small companies to back up data.
  •  They have a broad compatibility with a wide range of servers, operating systems, and backup ...

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