Hesela / Structured knowledge

Storage Knowledge Corpus

Storage definitions, connected to their evidence.

866 terms · Page 21 of 29

A-Z

  1. Term

    Raw bit error rate

    Raw bit error rate is the number of erroneous bits divided by the total bits read at a specified measurement point before error correction.

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  2. Term

    RDMA storage networking

    RDMA storage networking moves storage commands and data between hosts and storage systems with remote direct memory access, so data is placed directly into registered memory buffers without intermediate data copies; NVMe over Fabrics (NVMe/RDMA) and iSCSI Extensions for RDMA (iSER) are the standardised examples.

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  3. Term

    Read amplification

    Read amplification expresses storage-read work per logical read request or per useful byte returned, under an explicitly stated accounting convention.

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  4. Term

    Read disturb

    Read disturb is an unintended change in NAND cell thresholds caused by reads to other wordlines in the same block.

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  5. Term

    Read quorum

    A read quorum is a protocol-approved set of replicas whose responses satisfy the requirement for completing a read.

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  6. Term

    Read reclaim

    Read reclaim relocates valid NAND data to fresh pages to limit accumulated read-disturb errors.

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  7. Term

    Read repair

    Read repair reconciles divergent replicas as part of processing a read request.

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  8. Term

    Read-after-write verification

    Read-after-write verification checks stored data after a write, with comparison guarantees determined by the verification mechanism.

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  9. Term

    Read-modify-write

    A storage update that reads existing data needed to preserve unchanged information, combines it with replacement data, and writes the modified data and any required redundancy.

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  10. Term

    Read-only mount

    A read-only mount restricts filesystem modification through Linux mount state, whose scope can be a VFS mount node, the filesystem superblock, or both.

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  11. Term

    Read-pass voltage

    Read-pass voltage is the bias applied to unselected NAND wordlines to make their cells conduct while another wordline is sensed.

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  12. Term

    Read-your-writes

    Read-your-writes is a session guarantee requiring subsequent reads to use a state that incorporates the session's prior successful writes.

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  13. Term

    readahead (Linux syscall)

    The Linux readahead syscall requests advance loading of a file range into the page cache without advancing the open file description's offset.

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  14. Term

    Recall

    Recall is the fraction of observed positive outcomes identified by a classifier at a specified decision threshold.

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  15. Term

    Reconstruct-write

    A parity-array update method that computes new parity from incoming replacement data and unchanged data from the same stripe instead of updating old parity from old overwritten data.

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  16. Term

    Recovery point objective

    The recovery point objective specifies the point in time to which data must be recoverable after a disruption, commonly expressed as the maximum tolerable data-loss interval.

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  17. Term

    Recovery target

    A recovery target is the configured condition at which database log replay should stop.

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  18. Term

    Recovery time objective

    The recovery time objective sets the tolerable duration of resource unavailability before its effect on supported processes becomes unacceptable.

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  19. Term

    Reed–Solomon codes (storage)

    Reed–Solomon codes are maximum-distance-separable error-correcting codes over finite-field symbols that add n − k check symbols to k data symbols and can rebuild missing (erased) symbols, which is why storage systems use them for RAID 6 parity and erasure-coded object storage.

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  20. Term

    Reflink

    Filesystem support for sharing physical extents between files until one copy is modified.

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  21. Term

    RENAME_EXCHANGE

    RENAME_EXCHANGE is a Linux renameat2 flag that atomically swaps two existing pathname bindings.

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  22. Term

    RENAME_NOREPLACE

    RENAME_NOREPLACE is a Linux renameat2 flag that rejects a rename when its destination already exists.

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  23. Term

    Repair locality

    Repair locality is the number of helper fragments needed to recover a missing fragment under a specified erasure-code repair procedure.

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  24. Term

    Repair-read amplification

    Repair-read amplification is the ratio of bytes read during recovery to the explicitly stated quantity of lost data or lost encoded fragments being restored.

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  25. Term

    Replay attack

    A replay attack reuses previously valid data to induce acceptance in an unauthorized context.

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  26. Term

    Replication lag

    Replication lag is a difference in replication progress between a source and a replica, measured at a named processing stage in a stated unit.

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  27. Term

    Replication slot

    In PostgreSQL, a replication slot tracks a consumer's progress and retains WAL and other resources needed for that consumer to continue.

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  28. Term

    Resilver

    A resilver is ZFS's process of bringing a newly attached, replacement or out-of-date device into agreement with the data it must hold.

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  29. Term

    Restore test

    A restore test exercises recovery from backup material and checks whether the recovered data or selected system functions meet defined acceptance criteria.

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  30. Term

    Retention interference

    Retention interference is dependence of a flash cell's charge-retention behavior on the state of a neighboring cell.

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