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A block, a contiguous number of bytes, is the minimum unit of storage that is read from and written to a disk by a disk driver.The earliest disk drives had fixed block sizes (e.g. the IBM 350 disk storage unit (of the late 1950s) block size was 100 six-bit characters) but starting with the 1301 [8] IBM marketed subsystems that featured variable block sizes: a particular track could have blocks ...
USB Attached SCSI (UAS) or USB Attached SCSI Protocol (UASP) is a computer protocol used to move data to and from USB storage devices such as hard drives (HDDs), solid-state drives (SSDs), and thumb drives. UAS depends on the USB protocol, and uses the standard SCSI command set.
Solid-state hybrid drives (SSHDs) are based on the same principle, but integrate some amount of flash memory on board of a conventional drive instead of using a separate SSD. The flash layer in these drives can be accessed independently from the magnetic storage by the host using ATA-8 commands, allowing the operating system to manage it.
Flash-based storage does not suffer the limitation of a battery, but RAM-backed storage is faster and does not experience write amplification. [3] [8] [9] As a result of having no moving mechanical parts, solid-state storage has no data access latency required to move the media as in an electromechanical storage device.
Historically, most SSDs used buses such as SATA, SAS, or Fibre Channel for interfacing with the rest of a computer system. Since SSDs became available in mass markets, SATA has become the most typical way for connecting SSDs in personal computers; however, SATA was designed primarily for interfacing with mechanical hard disk drives (HDDs), and it became increasingly inadequate for SSDs, which ...
A flash drive (also thumb drive, memory stick, and pen drive/pendrive) [1] [note 1] is a data storage device that includes flash memory with an integrated USB interface. A typical USB drive is removable, rewritable, and smaller than an optical disc , and usually weighs less than 30 g (1 oz).
In practice, flash file systems are used only for Memory Technology Devices (MTDs), which are embedded flash memories that do not have a controller. Removable flash memory cards and USB flash drives have built-in controllers to manage MTD with dedicated algorithms, [2] [3] like wear leveling, bad block recovery, power loss recovery, garbage ...
The core idea of ReadyBoost is that a flash memory (e.g. a USB flash drive or an SSD) has a much faster seek time than a typical magnetic hard disk (less than 1 ms), allowing it to satisfy requests faster than reading files from the hard disk. It also leverages the inherent advantage of two parallel sources from which to read data, whereas ...