Hesela / Structured knowledge

Storage Knowledge Corpus

Storage definitions, connected to their evidence.

866 terms · Page 20 of 29

A-Z

  1. Term

    PRML detection

    Partial-response maximum-likelihood (PRML) detection recovers a recorded symbol sequence by equalizing readback to a chosen partial-response target and evaluating sequence likelihoods under a channel model.

    JSON

  2. Term

    Probability calibration

    Probability calibration is agreement between forecast probabilities and conditional event frequencies among observations receiving those probabilities.

    JSON

  3. Term

    Process I/O accounting

    Process I/O accounting attributes selected I/O activity to a process using counters whose meaning depends on the operation, ownership and accounting layer.

    JSON

  4. Term

    Process-associated record lock

    A process-associated record lock is a byte-range file lock whose ownership is attached to a process rather than to an open file description.

    JSON

  5. Term

    Program/erase cycle

    One complete program and erase of a NAND erase block, a core endurance metric.

    JSON

  6. Term

    Proof of ownership (deduplication)

    A proof of ownership lets a deduplication client demonstrate possession of file content beyond a short identifier to a storage service.

    JSON

  7. Term

    Proof of retrievability

    A proof of retrievability is a storage-auditing protocol whose security model requires file extraction from a prover that succeeds sufficiently often in verification.

    JSON

  8. Term

    Protection information (PI)

    Protection information is integrity metadata accompanying storage I/O, with checks determined by the protocol, protection format and participating layers.

    JSON

  9. Term

    Provable data possession

    Provable data possession is a challenge-response method for checking whether an untrusted storage service retains specified data without retrieving the entire file.

    JSON

  10. Term

    Pseudo-SLC (pSLC)

    Operation of multi-bit-capable NAND in one-bit-per-cell mode, trading storage density for single-bit behavior.

    JSON

  11. Term

    Purge sanitization

    Purge sanitization uses suitable logical or physical techniques to make target-data recovery infeasible even with current state-of-the-art laboratory techniques while potentially allowing the medium to be reused.

    JSON

  12. Term

    pwrite

    pwrite is a seekable-file operation that writes up to the requested byte count at an explicit offset without changing the open file description's current offset.

    JSON

  13. Term

    QLC SSD

    A QLC SSD uses NAND flash that encodes four bits per cell using sixteen threshold-voltage states.

    JSON

  14. Term

    Quad-level cell (QLC)

    NAND flash that stores four bits per cell using sixteen threshold-voltage states.

    JSON

  15. Term

    Quantile

    A quantile is a distribution threshold associated with a specified cumulative probability, whose estimate from a finite sample depends on the chosen convention.

    JSON

  16. Term

    Queue depth

    Queue depth is the number of outstanding I/O requests at a specified boundary, while a configured depth limit is the maximum or target allowed in flight.

    JSON

  17. Term

    Quorum intersection

    Quorum intersection is the property that every relevant pair of allowed quorums shares at least one replica.

    JSON

  18. Term

    Racetrack memory

    Racetrack memory is a proposed non-volatile memory in which bits are stored as a train of magnetic domains, separated by domain walls, along a magnetic nanowire and are shifted past a fixed write element and read element by current pulses; it is a research concept, not a shipping bulk store.

    JSON

  19. Term

    RAID

    Redundant Array of Independent Disks combines multiple drives for performance or fault tolerance.

    JSON

  20. Term

    RAID 10

    RAID 10 combines replicated data copies with striping across storage members.

    JSON

  21. Term

    RAID 5

    RAID 5 stripes data and distributed single parity across members so that one missing member can be reconstructed when the remaining required information is readable and consistent.

    JSON

  22. Term

    RAID 6

    RAID 6 uses dual parity protection to retain data after any two member failures, provided the remaining required data and redundancy are readable and consistent.

    JSON

  23. Term

    RAID rebuild

    A RAID rebuild reconstructs the required contents of a replacement or out-of-sync member from the array's surviving redundancy.

    JSON

  24. Term

    RAID tail hour

    In The Tail at Store, a RAID tail hour is a group-hour in which at least one data drive has an hourly average I/O latency at least twice its group's median.

    JSON

  25. Term

    RAID write hole

    The RAID write hole is the risk that interrupted member updates leave inconsistent parity and corrupt reconstruction of missing data.

    JSON

  26. Term

    RAIDZ

    RAIDZ is ZFS's distributed-parity virtual-device layout with one, two or three parity fragments and block-dependent stripe widths.

    JSON

  27. Term

    RAIDZ expansion

    RAIDZ expansion widens an existing RAIDZ virtual device by attaching another member and redistributing allocated space while retaining old blocks' data-to-parity ratios.

    JSON

  28. Term

    Range tombstone

    A range tombstone is a versioned deletion marker that suppresses covered older keys across an ordered key interval.

    JSON

  29. Term

    Rate of occurrence of failures

    The rate of occurrence of failures (ROCOF) is the derivative with respect to time of the expected cumulative failure count of a repairable system.

    JSON

  30. Term

    Rateless IBLT

    Rateless IBLT is a set-reconciliation scheme that streams additional coded symbols until the receiver can recover the set difference without first estimating its size.

    JSON