Quantum Corporation is a manufacturer of data storage devices and systems, including tape drive and disk-based systems. The company's headquarters is in San Jose, California. From its founding in 1980 until 2001, it was also a major disk storage manufacturer (usually second-place in market share behind Seagate), and was based in Milpitas, California. Quantum sold its hard disk drive business to Maxtor in 2001 and now focuses on integrated storage systems.

Quantum got its start when executives and designers from Shugart Associates, IBM and Memorex came up with an idea for an 8-inch hard drive that would achieve decent performance without the cost or complexity of using a full closed-loop servo system — a difficult task before the advent of dedicated servo ICs and readily available DSPs.

Early on, the company designed smaller ST-506-compatible versions of its hard drives, the Q500 series, using the same servo system. In 1985, it introduced the Plus Hardcard, which was essentially a smaller version of the Q500, designed to fit in an ISA slot. In 1986, Quantum entered the then-new SCSI market with the Q280 80MB drive, which was one of the first mass-market drives to use embedded servo. Later on, Quantum combined the Q280's embedded controller design with the servo hardware from the Q500 series, and developed the ProDrive range, which was also its first drive family to support the ATA interface.

When the company was started, low end drives generally used stepper motors, which were slow, noisy, and prone to reliability problems. Quantum developed an optical positioning system to guide the actuator arm in "gross motor" movements, using only the closed-loop servo for precisely aligning the heads to a specific track. This "glass scale" solution saved quite a bit of hardware as it only required a single 8-bit microcontroller to handle the entire servo system. The Q2000 and Q4000 were the first drives to use this technology. Later on, as track pitch narrowed, diffraction became a problem, and the decision was made to discontinue the system in favor of a fully magnetic embedded servo. The last drives to use the optical assist system were the ProDrive LPS 120 and 240 "Gemini" models, released in 1991.

The Fireball brand of hard drives were manufactured between 1995 and 2001. In 1995, 540 MB Fireball hard drives using ATA and SCSI were available. In 1997, the Fireball ST, available in 1.6 GB to 6.4 GB capacities, was considered a top performer, while the Fireball TM was significantly slower.

After some success with the Fireball AT 1080 and Fireball AT 1280 (both high-performance 5400 rpm models), Quantum skewed briefly toward drives that concentrated more on capacity than speed or performance. Later versions of the Fireball series reversed this trend, and eventually a 7200 rpm Fireball Plus ATA version was released. The first of the Plus series was the Fireball Plus KA, a drive available in sizes up to 18.2 gigabytes, and equipped with the new Ultra DMA 66 interface.

The Bigfoot brand of hard drives were available during the late 1990s and generally had lower costs per megabyte. It used a low-profile 5.25-inch form factor and larger disks to increase drive capacity without forcing an increase in areal density. However, the Bigfoot drives had slow spindles (the first ones ran at only 3600 rpm, long obsolete by then), and the larger disk diameters meant the heads had to move farther when seeking. They were thus generally disliked by "power users," and found their way mostly into inexpensive, brand-name PCs.

In July 1994, Quantum purchased DEC's data storage division. This gave Quantum access to the DLT streaming tape system, as well as Digital's design team in Shrewsbury, Massachusetts, which previously designed the RZ72 SCSI disk. The StorageWorks brand of disk arrays was not included in the deal.

After the acquisition, Quantum tasked the Shrewsbury design team with developing the Atlas series of SCSI disks. Quantum's Milpitas design team created the Viking, Phoenix and Katana designs.

Due to widespread Y2K fears, and the associated desire to safeguard data, the DLT product line had a large increase in sales in the late 1990s. As a result, Quantum split the company into two parts, one for the DLT products, and one for hard disk drives.

By 2000, the hard drive market was becoming less profitable. Quantum decided to sell its hard drive division to Maxtor at this time. The transfer took effect on April 1, 2001. Although Maxtor systematically eliminated much of the staff of Quantum's former hard drive division during the following year, it continued most of Quantum's disk storage products and brands until it was acquired by Seagate Technology on December 21, 2005.

Quantum purchased Meridian Data, developer of the Snap Server line of network attached storage products in 1999. This division was spun off in 2002 as Snap Appliance and was subsequently acquired by Adaptec in 2004.

A couple of years prior to the 2000 merger of the hard drive division, Quantum began a series of tape technology acquisitions:

Since 1994 when it acquired the Digital Linear Tape product line from Digital, Quantum has sold tape storage products, including tape drives, media and automation. In 2007, Quantum discontinued development of the DLT line in favor of Linear Tape-Open, which it began selling in 2005 following its acquisition of Certance.

Quantum's tape automation portfolio includes SuperLoader autoloaders and Scalar tape libraries. Its Scalar line, originally developed by ADIC, includes entry-level, midrange and enterprise products. Quantum's Scalar libraries incorporate iLayer management software and the Extended Data Life Management (EDLM) feature, which automatically evaluate the integrity of tape drives and media within the library.

Quantum's tape libraries are sold under the company's own brand as well through OEM partners, including Dell, HP and IBM.

In 2012, Quantum introduced its Scalar LTFS (Linear Tape File System) appliance, which offers new modes of portability and user accessibility for archived content on LTO tape.

Quantum introduced its first disk-based backup and recovery product, the DX30, in 2002 and has continued to build out this product line.

At the end of 2006, shortly after its acquisition of ADIC, Quantum announced the first of its DXi-Series products incorporating data deduplication technology which ADIC had acquired from a small Australian company called Rocksoft earlier that year. Since then, Quantum has expanded and enhanced this product line and now offers DXi solutions for SMB, midrange and enterprise customers. In 2012, Quantum also announced a virtual deduplication appliance, the DXi V1000.

DXi-Series products incorporate Quantum’s patented data deduplication technology, providing typical data reduction ratios of 15:1 or 93%. The company offers both target and source-based deduplication as well as integrated path-to-tape capability. DXi works with all major backup applications, including Symantec's OpenStorage (OST) API, and supports everything from remote offices to corporate data centers. Quantum includes all software licenses for each model in the base price.

In addition to its DXi-Series of disk backup products, Quantum also offers its RDX removable disk libraries and NDX-8 NAS appliances for data protection in small business environments. The company introduced these products in 2011.

Quantum's vmPRO software and appliances are used for protecting virtual machine (VM) data. vmPRO software works with DXi appliances and users' existing backup applications to integrate VM backup and recovery into their existing data protection processes. It auto-discovers VMs and presents a file system view, allowing users to back up VMs or files within VMs without adding VM-specific agents. When data is read through the vmPRO software, inactive data is filtered out, reducing backup volumes by up to 75% and boosting deduplication rates. To support fast recovery, vmPRO software augments traditional backup with a simple VM snapshot utility that creates native-format VM copies on secondary disk, allowing restore at a VM or at a single file level.

In March 2012, Quantum announced that its vmPRO technology and DXi V1000 virtual appliance had been selected by Xerox as a key component of the company's a key component of Xerox's cloud backup and disaster recovery (DR) services.

In August 2012, Quantum announced Q-Cloud, its own branded cloud-based data protection service, which is also based on vmPRO and DXi technology. Q-Cloud provides backup of both physical and virtual infrastructures for capacities ranging from 1 TB up to 1 PB of protected data.

Quantum's acquisition of ADIC in 2006 included ADIC’s StorNext File System (SNFS) and archive product line. SNFS delivers high-performance file access in environments where large files must be shared by users without network delays, such as analyzing real-time satellite image data, or where a file must be available for access by multiple readers starting at different times, such as on-demand access of a movie stored on disk. SNFS also supports heterogeneous environments across Linux, Mac, Unix, and Windows operating systems.

Now in its fourth generation, StorNext has been in use for almost two decades in a number of vertical markets, including media and entertainment, government surveillance, oil and gas, and life sciences.

In 2011, the company added the StorNext appliance offerings to its product family. In addition to the StorNext Archive Enabled Library (AEL), the company added a metadata controller (StorNext M330), a scale-out gateway appliance (G300), and several scalable storage systems (QM1200, QS1200 and QD6000). In February 2012, the company bolstered the StorNext appliance family with the addition of the QS2400 Storage System, followed in July by the M660 metadata appliance.

In late 2012, Quantum introduced the Lattus product family OEM'd from Amplidata, a scale-out object storage system composed of storage nodes, access nodes and controller nodes that are built for multiple petabyte data stores. Lattus-X is the first of a series of disk-based archives in the Lattus family that includes a native HTTP REST interface, and CIFS and NFS access to applications.

The Lattus wide area storage solution is built on a version of object storage called fountain coding. Fountain code provides the same level of protection as Reed–Solomon error correction but with more data protection and higher efficiencies. Quantum sees wide area storage (a term coined by the company) as another storage tier complementing traditional disk and tape.