Carnegie Mellon had sued Marvell in March 2009 over patents issued that related to how accurately hard disk drive circuits read data from high-speed magnetic disks.
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Atomic memory can achieve information density of 502 terabits per square inch Instead of using magnetic disks or integrated circuits, like today's hard drives and solid state drives, the new technology, known as atomic memory, uses an arrangement of individual atoms to store data.
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Most magnetic storage devices use error correction. Many magnetic disks internally use some form of run-length limited coding and partial-response maximum-likelihood.
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The IBM 1401 offered new media for data, tapes and magnetic disks (8Kb memory). 10 years after the purchase of this computer, punched cards were replaced by 5,000 tapes and 150 magnetic disks. The bank bought a data encoding service and check post-marking service. From 1978 onwards, the first branch terminals could consult the central information system, hosted in Créteil new offices and IT jobs became more and more important.
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During the following years, mainly punched cards were used. Over the course of the 1960s, a gradual transition took place to other media, such as journal strips, magnetic tapes and magnetic disks.
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Viscous Circle is a story about a strange and inhuman race of beings and an experimental attempt to transfer into creatures that seem only slightly sapient. They are ultimate pacifists that take the form of magnetic disks that float through space and simply demagnetize and destroy themselves when faced with an unpleasant thought.
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OAM was created in the 1980s "as a prototype product for an insurance company to replace microfiche." Initially OAM supported optical storage and magnetic disks. In the 1990s support for magnetic tape was added. In 2011 support was added for storage of objects in a z/OS unix file system-- either zFS or NFS.
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Iron(III) oxide was the most common magnetic particle used in all types of magnetic storage and recording media, including magnetic disks (for data storage) and magnetic tape (used in audio and video recording as well as data storage). Its use in computer disks was superseded by cobalt alloy, enabling thinner magnetic films with higher storage density.
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Advanced Format (AF) is any disk sector format used to store data on magnetic disks in hard disk drives (HDDs) that exceeds 512, 520, or 528 bytes per sector, such as the 4096, 4112, 4160, and 4224-byte (4 KB) sectors of an Advanced Format Drive (AFD). Larger sectors enable the integration of stronger error correction algorithms to maintain data integrity at higher storage densities.
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In IBM mainframe operating systems, Basic sequential access method (BSAM) is an access method to read and write datasets sequentially. BSAM is available on OS/360, OS/VS2, MVS, z/OS, and related operating systems. BSAM is used for devices that are naturally sequential, such as punched card readers, punches, line printers, and magnetic tape. It is also used for data on devices that could also be addressed directly, such as magnetic disks.
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Section "Hard Disk Platters (Disks)". 1998\. In 2005–06, a major shift in technology of hard-disk drives and of magnetic disks/media began. Originally, in-plane magnetized materials were used to store the bits but has now been replaced by perpendicular recording. The reason for this transition is the need to continue the trend of increasing storage densities, with perpendicularly oriented media offering a more stable solution for a decreasing bit size.
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In the mid-1990s, a consortium of manufacturers (Sony, Philips, Toshiba, Panasonic) developed the second generation of the optical disc, the DVD. Magnetic disks found limited applications in storing the data in large amount. So, there was the need of finding some more data storing techniques. As a result, it was found that by using optical means large data storing devices can be made that in turn gave rise to the optical discs.
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Since the crucial function of a file server is storage, technology has been developed to operate multiple disk drives together as a team, forming a disk array. A disk array typically has cache (temporary memory storage that is faster than the magnetic disks), as well as advanced functions like RAID and storage virtualization. Typically disk arrays increase level of availability by using redundant components other than RAID, such as power supplies. Disk arrays may be consolidated or virtualized in a SAN.
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In IBM mainframe operating systems, queued sequential access method (QSAM) is an access method to read and write datasets sequentially. QSAM is available on OS/360, OS/VS2, MVS, z/OS, and related operating systems. QSAM is used both for devices that are naturally sequential, such as punched card readers and punches and line printers, and for data on devices that could also be addressed directly, such as magnetic disks. QSAM offers device independence: to the extent possible, the same API calls are used for different devices.
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Data on modern disks is stored in fixed length blocks, usually called sectors and varying in length from a few hundred to many thousands of bytes. Gross disk drive capacity is simply the number of disk surfaces times the number of blocks/surface times the number of bytes/block. In certain legacy IBM CKD drives the data was stored on magnetic disks with variable length blocks, called records; record length could vary on and between disks. Capacity decreased as record length decreased due to the necessary gaps between blocks.
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System, pg. 8 The core memory was backed by one or two magnetic drums with 16k words each.System, pg. 18 Various offline input/output included magnetic disks, tape drives, punched cards, punched tape and printers. Most of the Orion's instruction set used a three- address form, with sixty-four 48-bit accumulators. Each program had its own private accumulator set which were the first 64 registers of its address space, which was a reserved contiguous subset of the physical store, defined by the contents of a "datum" relocation register.
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Even overwriting the portion of a disk surface occupied by a deleted file is insufficient in many cases. Peter Gutmann of the University of Auckland wrote a celebrated 1996 paper on the recovery of overwritten information from magnetic disks; areal storage densities have gotten much higher since then, so this sort of recovery is likely to be more difficult than it was when Gutmann wrote. Modern hard drives automatically remap failing sectors, moving data to good sectors. This process makes information on those failing, excluded sectors invisible to the file system and normal applications.
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In 1972, Stephen Bernard Dorsey, Founder and President of Canadian company Automatic Electronic Systems (AES), introduced the world’s first programmable word processor with a video screen. The real breakthrough by Dorsey’s AES team was that their machine stored the operator’s texts on magnetic disks. Texts could be retrieved from the disks simply by entering their names at the keyboard. More importantly, a text could be edited, for instance a paragraph moved to a new place, or a spelling error corrected, and these changes were recorded on the magnetic disk.
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SpinRite tests the data surfaces of writeable magnetic disks, including IDE, SATA, and floppy disks. It analyzes their contents and can refresh the magnetic disk surfaces to allow them to operate more reliably. SpinRite attempts to recover data from hard disks with damaged portions that may not be readable via the operating system. When the program encounters a sector with errors that cannot be corrected by the disk drive's error-correcting code, it tries to read the sector up to 2000 times, in order to determine, by comparing the successive results, the most probable value of each bit.
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The entire process typically occurs with little or no degradation in performance. The translation process is more complicated when writing data that is either not a multiple of 4K or not aligned to a 4K boundary. In these instances, the hard drive must read the entire 4096-byte sector containing the targeted data into internal memory, integrate the new data into the previously existing data and then rewrite the entire 4096-byte sector onto the disk media. This operation, known as read- modify-write (RMW), can require additional revolution of the magnetic disks, resulting in a perceptible performance impact to the system user.
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MINIMOP was an operating system which ran on the International Computers Limited (ICL) 1900 series of computers. MINIMOP provided an on-line, time- sharing environment (Multiple Online Programming, or MOP in ICL terminology), and typically ran alongside George 2 running batch jobs. MINIMOP was named to reflect its role as an alternative to the MOP facilities of George 3, which required a more powerful machine. MINIMOP would run on all 1900 processors apart from the low-end 1901 and 1902 and required only 16K words of memory and two 4 or 8 million character magnetic disks.
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The sizes, capabilities, and performance of databases and their respective DBMSs have grown in orders of magnitude. These performance increases were enabled by the technology progress in the areas of processors, computer memory, computer storage, and computer networks. The concept of a database was made possible by the emergence of direct access storage media such as magnetic disks, which became widely available in the mid 1960s; earlier systems relied on sequential storage of data on magnetic tape. The subsequent development of database technology can be divided into three eras based on data model or structure: navigational, SQL/relational, and post-relational.
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Soundwave is one of the most recognizable characters from the original Transformers line, because of his alternate mode – a microcassette recorder – and his distinctive monotone, computerized voice. Soundwave is able to detect and jam transmissions across the entire energy spectrum, a talent that makes him suited to his position as Decepticon Communications Officer. Additionally, he has a photographic memory thanks to the vast data storage capacity of the magnetic disks in his chest compartment, and he is armed with a shoulder- mounted laser cannon and hand-held concussion blaster. Soundwave is physically strong compared to most Transformers.
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Logical volumes can suffer from external fragmentation when the underlying storage devices do not allocate their PEs contiguously. This can reduce I/O performance on slow-seeking media such as magnetic disks and other rotational media. Volume managers that use fixed-size PEs, however, typically make PEs relatively large (for example, Linux LVM uses 4 MB by default) in order to amortize the cost of these seeks. With implementations that are solely volume management, such as Core Storage and Linux LVM, separating and abstracting away volume management from the file system loses the ability to easily make storage decisions for particular files or directories.
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All codes used to record on magnetic disks have limited the length of transition-free runs and can therefore be characterized as RLL codes. The earliest and simplest variants were given specific names, such as modified frequency modulation (MFM), and the name "RLL" is commonly used only for the more complex variants not given such specific names, but the term technically applies to them all. The first "RLL" code used in hard drives was RLL (2,7), developed by IBM engineers and first used commercially in 1979 on the IBM 3370 DASD,A Quarter Century of Disk File Innovation, IBM Journal of Research and Development.P. A. Franaszek (1972), “Run-Length-Limited Variable Length Coding with Error Propagation Limitation”, .
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To make it readable in CD-ROM and DVD-ROM drives, the disc can be closed at any time by writing a final table-of-contents to the start of the disc; thereafter, the disc cannot be packet-written any further. Packet writing, together with support from the operating system and a file system like UDF, can be used to mimic random write-access as in media like flash memory and magnetic disks. Fixed-length packet writing (on CD-RW and DVD-RW media) divides up the disc into padded, fixed-size packets. The padding reduces the capacity of the disc, but allows the recorder to start and stop recording on an individual packet without affecting its neighbours.
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In this way, no single erase block prematurely fails due to a high concentration of write cycles."Algorithms and data structures for flash memories", E. Gal, and S. Toledo, ACM Computing Surveys, 2005 In flash memory, a single block on the chip is designed for longer life than the others so that the memory controller can store operational data with less chance of its corruption. Conventional file systems such as FAT, UFS, HFS, ext2, and NTFS were originally designed for magnetic disks and as such rewrite many of their data structures (such as their directories) repeatedly to the same area. When these systems are used on flash memory media, this becomes a problem.
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The is a magnetic disk drive peripheral for the Nintendo 64 game console developed by Nintendo. It was announced in 1995, prior to the Nintendo 64's 1996 launch, and after numerous delays was released only in Japan on December 1, 1999. The "64" references both the Nintendo 64 console and the 64 MB storage capacity of the disks, and "DD" is short for "disk drive" or "dynamic drive". Plugging into the extension port on the underside of the console, the 64DD allows the Nintendo 64 to use proprietary 64 MB magnetic disks for expanded and rewritable data storage, a real-time clock for persistent game world design, and a standard font and audio library for further storage efficiency.
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In this state her personality is rather turned "overmasculine", loving to eat, fight, blow things up, and apparently possessing few other interests. The "Asura" form can create lightning storms, or small flaming rocks from her hands, sheathe her body in protective fire, and manifest a turbulent revolving inferno (literal "fire storm"), as well as emit a blinding flash of light. She is susceptible to physical attacks, and her mind is split in three parts that recurrently have different ideas of what to do, but her tendency to hover far away and attack from a distance makes her a difficult opponent. She later learns that her "power sources" are actually magnetic disks used to prevent stiffening in one's back, which is a problem for her cursed form.
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Magnetic disks are the predominant storage media in personal computers. Optical discs, however, are almost exclusively used in the large-scale distribution of retail software, music and movies because of the cost and manufacturing efficiency of the molding process used to produce DVD and compact discs and the nearly-universal presence of reader drives in personal computers and consumer appliances. Flash memory (in particular, NAND flash) has an established and growing niche as a replacement for magnetic hard disks in high performance enterprise computing installations due to its robustness stemming from its lack of moving parts, and its inherently much lower latency when compared to conventional magnetic hard drive solutions. Flash memory has also long been popular as removable storage such as USB sticks, where it de facto makes up the market.
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These addresses referred to specific locations on the disc in which a transducer was either commanded to write-in or read-out data. Goddard’s research began in the early 1950s at IBM’s Laboratory located on 99 Notre Dame Avenue in San Jose, CA. He did not see his work as particularly complex. As he puts it, “it was not high tech, or very scientific. It was more like something you’d do in your garage.” The IBM 350 Disk Storage Unit consisted of the magnetic disk memory unit with an access mechanism, the controls for the access mechanism, and a small air compressor. Assembled with covers, the 350 apparatus was 60 inches (1.52 m) long, 68 inches (1.73 m) high and 29 inches (0.74 m) deep. It was configured with 50 magnetic disks containing 50,000 sectors, each of which held 100 six-bit alphanumeric characters, for a capacity of 5 million six-bit characters.
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The process of moving portions of the command interpretation off the controller card and onto the drive itself in order to improve performance is a common feature of later hard drive connection schemes, notably SCSI, with its rich command set, and the storage-focused IDE systems. IDE, in effect, is a system for extending the computer bus so the interface controller can be built into the drive unit rather than being plugged into the computer's backplane. This allows a single "controller" card--really just an interface card--to communicate with multiple dissimilar drives, while it also reduces latency and noise between the controller and drive hardware. Effectively, the roles are reversed: instead of the controller doing almost all of the complex processing and the drive just transferring encoded data between the magnetic disks and the controller, the drive does almost all of the complex processing and the "controller" just transfers decoded data between the drive and the host system.
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Since a common SSD has no knowledge of the file system structures, including the list of unused blocks/sectors, the storage medium remains unaware that the blocks have become available. While this often enables undelete tools to recover files from electromechanical hard disks, despite the files being reported as "deleted" by the operating system, it also means that when the operating system later performs a write operation to one of the sectors, which it considers free space, it effectively becomes an overwrite operation from the point of view of the storage medium. For magnetic disks, an overwrite of existing data is no different from writing into an empty sector, but because of how some SSDs function at the lowest level, an overwrite produces significant overhead compared to writing data into an empty page, potentially crippling write performance. SSDs store data in flash memory cells that are grouped into pages typically of 4 to 16 kiB, grouped together into blocks of typically 128 to 512 pages.
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