2024-12-24

magnetic tape

General Knowledge Of Magnetic Tape

DATARECOVERYUNION.COM06 mins

History of Magnetic Tape & Magnetic Disks

Magnetic tape and magnetic disk media are used for data storage.They have developed and changed over the years, getting smaller while holding more information.

As a rule, size of media has moved from being enormous and very inefficient, to tiny and ultra-efficient. We have seen magnetic tape with a 2-inch width being replaced by micro-miniature disks holding hundreds of times the capacity and with much more redundancy.

Magnetic tape and disks have been used to store all manner of material, from raw data to music and video. They were found to be an efficient and convenient way of storage, well-purposed for analog and digital content. In fact, the transition from analog to digital was made easy by magnetic storage.

A magnetic tape must be rewound. A disk needs rapid navigation to leverage the content quickly, and this is why disks have quickly become the media of choice. In spite of this, IBM ensured that tape rewind distance be minimized by a return to the middle of the tape.

Magnetic media will constantly move from large static arrays to smaller replaceable and redundant arrays. Tape is rapidly losing its usefulness.

The first magnetic tapes were loaded on open reels and needed rewinding. There were also tapes in cartridges that required no rewinding. However, this gave way to disk, which was easier to manipulate and not subject to jamming and breaking.

Use of Magnetic Tape in Computers

Floppy disks use magnets to store data, as do most hard drives. The earliest form of disk storage involved magnetic tape on reels. These early disk drives retrieved data more slowly than modern disk drives. Magnetic tape drives still see use even in the most modern of Information Technology departments. The relatively low cost of magnetic tape systems means that IT departments save money by using magnetic computer tape drives.

Function

Magnetic tape systems store large amounts of data cheaply. Tape systems come in reel-to-reel formats similar to the ones movie projectors use and in formats that look like audio cassette tapes. Backup of large amounts of data is the primary use for magnetic tape systems.

Access Times

Tape drives write data onto a magnetic computer tape in sequential order. When someone needs to get data off of the drive, the system must seek the exact data the person looks for. Unlike a hard drive or a disk drive where multiple read/write heads allow the drive to find the requested data quickly, a tape drive can only read one portion of a tape at a time.

Cassettes Hold More Data

Reel to reel drives take up more space than the cassette models, but typically hold less information. The packaging for magnetic tape indicates how much information a tape can hold. Magnetic tape, like floppy disks has a density. Higher density tape allows a drive to store more data in smaller sections of tape. The BPI rating determines how many bits a single inch of tape can hold. BPI stands for “bits per inch.”

Backup Frequency

Because of the amount of time it takes to read and write from tape drives, most businesses using this system back up their data once a day and a back up the entire system once per week. The backup process takes several hours and almost always occurs after the close of business.

Where Each Type Gets Used

Older computer networks use reel to reel systems to back up the data. Newer computer networks use drives that more closely resemble audio cassettes. Computers have not run programs off tape drives since the 1980s. Floppy and hard disks were more efficient ways of accessing programs. The newer technology of flash drives allows for an extremely portable form of data storage. Magnetic computer tape may eventually fall into disfavor.

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Hard Drive Storage Vs Magnetic Tape

DATARECOVERYUNION.COM06 mins

Hard drive storage is quite different from magnetic tape, though both of them are usually used for backup solutions. Both technologies operate on the same basic principles, which have been in use for over 60 years. The benefits and pitfalls of each make them best suited to different situations, however.

Basics of Magnetic Storage

On any magnetic storage medium, information is encoded into binary, then recorded by setting the polarity of many tiny regions on the media. This pattern of positives and negatives is a relatively resilient form of non-volatile memory and forms the basis for the majority of digital information storage. The size of the regions are only limited by the technology of the read and write mechanisms, and they have become much smaller in recent years. This allows more data to fit in the same space, which means more storage on hard drives and tapes without changing their physical dimensions.

Hard Drives

A hard drive operates like a group of record players stacked on top of each other. Several platters spin on a common spindle, and an arm moves to place read/write devices–the heads, analogous to turntable cartridges–over specific parts of each platter to read or change polarities of portions (sectors) of the platter.

The platter is typically made of glass or a non-magnetic alloy, coated with a thin layer of a ferromagnetic material. The platter is spun at very high speeds (up to 10,000 rpm), and the common arm moves to give the heads access to almost every part of the platter.
Unfortunately, the mechanical nature of hard drives makes them prone to failure, and data loss is not uncommon.

Tape Drives

Digital tape has been in use for over 50 years, and it remains a very common storage solution. Modern tape solutions use interchangeable tape cartridges in a fixed tape drive and often use a mechanical loader to automate cartridge switching.

Like a hard drive, positive and negative charges are written to a magnetized medium. In a digital ape, that medium is a half-inch wide magnetized ribbon. Blocks of data are stored in contiguous regions on the tape, but finding the desired region to read data back can take a lot of winding. Tape drives wind backward and forward automatically to find the requested data, but wait times can still be upward of 60 seconds. Modern tape drives can deliver 80 megabytes per second once transfer begins, however.

Digital tape is the most inexpensive mass storage medium, and for this reason it is still in widespread use for mass data operations. It is also less prone to mechanical failure and data loss than hard drives, but the extreme access time is a major issue with many implementations.

Common Uses: Hard Drives

Hard drives have the advantage of fast data seek times, and though the cost per byte is not as low as that of digital tapes, it is low enough for many purposes. Hard disks are most commonly used as the primary storage for computers, but they are also often used as backup media. The failure rate of hard drives is too high however, for a single drive to serve as an adequate failsafe. Many organizations connect multiple hard drives together in a RAID array for redundancy, or simply keep a second hard drive as a backup of their backup.
Modern hard drives are available as large as 2 terabytes, enough for many backup needs. This is an economical data storage solution for most users, but not necessarily a good long term one.

Common Uses: Tape Drives

Tape drives are the most inexpensive way to store massive amounts of data. Though individual tapes do not reach beyond the 2 terabytes offered by hard drive storage, they are significantly less expensive, more durable and often support spanning data across multiple tapes for extremely large files. Tapes still offer the most failure-resistant long-term backup solution available, particularly for large quantities of data.

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