Hesela / Structured knowledge

Storage Knowledge Corpus

Storage definitions, connected to their evidence.

866 terms · Page 28 of 29

A-Z

  1. Term

    Value log

    A value log is an append-oriented record store whose values are located through a separate index.

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  2. Term

    Virtual eXecutable Archive

    A Virtual eXecutable Archive packages decoding programs with encoded content for execution in a specified virtual environment.

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  3. Term

    Volume manager

    Host or array software that groups physical drives into logical volumes and snapshots.

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  4. Term

    WAL archiving

    WAL archiving preserves write-ahead-log segments for later recovery before normal log recycling can remove them.

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  5. Term

    WAL compression

    PostgreSQL WAL compression optionally compresses full-page images within its write-ahead log.

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  6. Term

    Warm storage tier

    A warm storage tier holds online data whose request rate has fallen well below that of new data but is not zero, on capacity-optimised storage (for example erasure-coded disks sized for about 20 IOPS per terabyte), between the hot tier and cold or archive storage that can take hours or days to retrieve.

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  7. Term

    Wear leveling

    Wear leveling is flash management that distributes program/erase activity among blocks to reduce uneven wear.

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  8. Term

    Winchester disk architecture

    Winchester disk architecture combines low-mass, lightly loaded flying heads with lubricated disks in a protected head-disk assembly; it does not require non-removable media.

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  9. Term

    Workload rate limit

    A workload rate limit is a manufacturer-specified HDD operating workload bound, commonly expressed as host reads plus writes in terabytes per 8,760 power-on hours.

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  10. Term

    WORM storage

    Write-once-read-many storage preserves recorded content against subsequent alteration while allowing repeated reads.

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  11. Term

    Write amplification

    Device-level byte write amplification is the ratio of bytes programmed to the storage medium to bytes written by the host over the same accounting interval.

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  12. Term

    Write combining

    Write combining here means collecting small or scattered writes in a buffer and issuing them as fewer, larger, ordered operations, so that flash sees fewer partial-block merges and shingled disks see fewer read-modify-write rewrites of a band; it reduces write amplification but needs a buffer that survives power loss.

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  13. Term

    Write quorum

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

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  14. Term

    Write skew

    Write skew is a concurrency anomaly in which transactions read overlapping data and make disjoint writes whose combined outcome can violate an invariant that each transaction would preserve alone.

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  15. Term

    Write-ahead log

    A write-ahead log is a recovery log whose relevant records must become durable before the corresponding changes are persisted in database data files.

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  16. Term

    Write-back cache

    Write-back caching completes a write after updating the cache and defers updating its backing store until later.

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  17. Term

    Write-intent bitmap

    A write-intent bitmap tracks regions of a redundant array that may need synchronization after interrupted writes.

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  18. Term

    Write-once media

    Storage that physically or logically prevents rewriting committed regions.

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  19. Term

    Write-through cache

    Write-through caching propagates writes to the backing store as part of completing them at the cache layer.

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  20. Term

    Writeback error

    A writeback error is a failure encountered while transferring modified cached data to its backing storage.

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  21. Term

    Writes-follow-reads

    Writes-follow-reads requires every replica incorporating a session write to incorporate and order before it the updates relevant to that session's earlier reads.

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  22. Term

    writev

    writev is a vectored I/O operation that writes an ordered array of buffers to a file descriptor and reports the total number of bytes transferred.

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  23. Term

    XFS Active Item List

    The XFS Active Item List tracks logged items whose journal records remain needed until later retirement.

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  24. Term

    XFS Committed Item List

    The XFS Committed Item List tracks in-memory logged changes awaiting a journal checkpoint.

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  25. Term

    XFS deferred operation

    An XFS deferred operation postpones metadata work to a later transaction to satisfy locking or reservation constraints.

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  26. Term

    XFS delayed logging

    XFS delayed logging aggregates metadata changes in memory before committing them to the filesystem journal.

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  27. Term

    XFS intent log item

    An XFS intent log item describes deferred work that log recovery may need to complete.

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  28. Term

    XFS relogging

    XFS relogging records an object's outstanding metadata changes again in a newer transaction.

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  29. Term

    XFS rolling transaction

    An XFS rolling transaction commits one step of a transaction chain and continues with a fresh transaction using a permanent log reservation.

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  30. Term

    XOR filter

    An XOR filter is a static approximate-membership structure whose lookup compares a key fingerprint with the XOR of shared array entries.

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