Hesela / Structured knowledge

Storage Knowledge Corpus

Storage definitions, connected to their evidence.

866 terms · Page 6 of 29

A-Z

  1. Term

    Disk shelf

    A disk shelf is a rack-mounted enclosure that provides power, cooling and SAS connectivity to a group of drives and reports its state through SCSI Enclosure Services; one open hardware specification, for example, describes a 2U unit holding 30 3.5-inch drives.

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  2. Term

    Distributed snapshot

    A distributed snapshot records a coordinated global state of participating processes and their communication channels.

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  3. Term

    Distributed spare

    A distributed spare is replacement capacity spread across multiple devices rather than reserved on a single dedicated spare device.

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  4. Term

    DLT

    Digital Linear Tape (DLT) is a family of half-inch (12,7 mm) single-reel linear serpentine tape cartridges and drives, standardised by ECMA as DLT 1 to DLT 6 and extended by later Super DLT and DLT-S generations, used mainly for mid-range backup before LTO became the more common choice.

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  5. Term

    dm-crypt

    dm-crypt is a Linux device-mapper target that transparently encrypts and decrypts block-device I/O using the kernel cryptographic API.

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  6. Term

    dm-integrity

    dm-integrity is a Linux device-mapper target that stores per-block integrity tags and can generate and verify them when configured with an internal hash.

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  7. Term

    dm-integrity recovery mode

    dm-integrity recovery mode is a Linux device-mapper access mode that bypasses integrity checks and journal replay while disallowing writes through the mapping.

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  8. Term

    dm-verity

    dm-verity is a Linux device-mapper target that verifies a read-only block mapping against a trusted cryptographic root hash.

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  9. Term

    DNA data storage

    DNA data storage represents digital information in nucleotide sequences that are synthesized, preserved and read back for decoding.

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  10. Term

    Doublewrite buffer

    An InnoDB doublewrite buffer stages data-page copies before their final file writes so crash recovery can repair an incomplete page write.

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  11. Term

    Drive firmware revision

    A drive firmware revision is the vendor-assigned version identifier reported for the firmware running on a storage drive.

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  12. Term

    Drive-day

    A drive-day is one drive observed in operation for one day, used as a unit of fleet exposure.

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  13. Term

    Drum memory

    Early rotating magnetic drum storage where data was recorded on the outer surface of a metal cylinder.

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  14. Term

    Dual-actuator HDD

    A dual-actuator HDD is a hard drive with two independently positioning head assemblies that can service different data regions concurrently.

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  15. Term

    Dual-port drive

    A dual-port drive exposes two independent ports (two SAS ports with separate SAS addresses, or an NVMe subsystem with more than one port and two or more controllers) to the same media, so a host can keep reaching the data over a second path in multipath arrays.

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  16. Term

    Dual-stage actuator (HDD)

    A dual-stage HDD actuator combines a coarse positioning stage with a fine positioning stage to control the read/write head.

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  17. Term

    DVD PI Sum8

    DVD PI Sum8 counts parity-inner rows containing errors over eight consecutive ECC blocks before correction.

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  18. Term

    DWPD

    DWPD is an SSD endurance rating that normalizes cumulative host writes by host-addressable drive capacity and the number of days in a specified period.

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  19. Term

    Dynamic layout score

    Dynamic layout score is a workload-specific locality measure based on the fraction of traced filesystem block requests that are contiguous in logical block address space.

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  20. Term

    Dynamic Merkle Tree

    A Dynamic Merkle Tree is a research hash-tree design that adapts its shape to storage access patterns to reduce authentication-path costs.

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  21. Term

    Dynamic wear leveling

    Dynamic wear leveling distributes wear through placement of incoming writes among eligible free flash blocks.

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  22. Term

    E1.S

    A short EDSFF SSD form factor aimed at 1U servers with power and thermal profiles between M.2 and U.2.

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  23. Term

    Early retention loss

    Early retention loss is the rapid initial charge-loss behavior observed after programming some NAND cells.

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  24. Term

    EDSFF

    A family of ruler and short SSD form factors for dense NVMe deployment in servers and JBOD enclosures.

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  25. Term

    Effective spare factor

    Effective spare factor is the fraction of a modeled SSD's physical page capacity not occupied by valid logical data at a specified time.

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  26. Term

    eMMC (embedded MultiMediaCard)

    eMMC is a JEDEC-standard managed-flash device that combines NAND memory and a controller in one package and communicates through a parallel MMC interface.

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  27. Term

    End-to-end data protection

    End-to-end data protection is an integrity scheme whose generation and verification points span an explicitly defined data path.

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  28. Term

    Energy-assisted perpendicular magnetic recording (ePMR)

    Energy-assisted perpendicular magnetic recording (ePMR) is Western Digital's write-assist approach in which a DC bias through the write pole makes the write field more consistent, reducing recording jitter.

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  29. Term

    Enterprise SSD

    An enterprise SSD is a solid-state drive intended for server, storage-array or other multi-user storage environments.

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  30. Term

    Entity tag

    An entity tag is an opaque HTTP validator assigned by a server to a selected representation for cache validation and conditional requests.

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