Hesela / Structured knowledge

Storage Knowledge Corpus

Storage definitions, connected to their evidence.

866 terms · Page 18 of 29

A-Z

  1. Term

    Open-zone limit

    An open-zone limit caps the zones simultaneously in implicitly open or explicitly open states.

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  2. Term

    Optical archival storage

    Optical archival storage preserves data on removable laser-readable media as part of a long-term retention and migration workflow.

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  3. Term

    Optical jukebox

    An optical jukebox is a robotic library in which a picker moves removable optical discs (CD, DVD, magneto-optical or Blu-ray) between storage slots and one or more drives, so that many more discs than drives can be reached without an operator.

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  4. Term

    Optical storage voxel

    An optical storage voxel is a localized modification inside a transparent medium whose measurable optical properties encode a data symbol.

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  5. Term

    Optical-disc lifetime estimate

    An optical-disc lifetime estimate predicts time to a defined error threshold for a stated population percentile and storage environment under an aging model.

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  6. Term

    OptiNAND

    OptiNAND is a flash-assisted HDD architecture that integrates an embedded iNAND device with disk-controller hardware and firmware.

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  7. Term

    Over-provisioning

    SSD over-provisioning is flash capacity withheld from host-addressable user storage to support controller management such as garbage collection and wear leveling.

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  8. Term

    Page cache

    The page cache is the kernel-managed memory that holds cached file contents for access and writeback.

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  9. Term

    Page LSN

    A page LSN records the log sequence number of the latest logged change reflected in a database page under the engine's recovery protocol.

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  10. Term

    Page-level mapping (FTL)

    Page-level mapping assigns physical flash locations independently to logical pages.

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  11. Term

    Parity declustering

    Parity declustering places parity groups across a larger device pool to distribute reconstruction work.

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  12. Term

    Parity inconsistency

    A parity inconsistency is a disagreement between stored parity and parity recomputed from the associated data blocks.

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  13. Term

    Parity pollution

    Parity pollution is propagation of incorrect data into redundancy information through parity calculations.

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  14. Term

    Parity RAID

    Parity RAID uses computed redundancy across striped data to reconstruct missing chunks without storing complete mirrored copies.

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  15. Term

    Parquet column chunk

    A Parquet column chunk is a contiguous sequence of encoded pages for one column within one row group.

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  16. Term

    Parquet page checksum

    A Parquet page checksum is an optional CRC32 value used to detect changes in the serialized page body, excluding its page header.

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  17. Term

    Parquet row group

    A Parquet row group is a logical partition of rows represented by one column chunk for each column.

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  18. Term

    Partial Parity Log

    Partial Parity Log is a Linux MD RAID5 mechanism that records the XOR of untouched stripe chunks before dispatching data and parity updates.

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  19. Term

    Partial quorum

    A partial quorum configuration allows a read response set and a write acknowledgement set that need not overlap.

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  20. Term

    Partition alignment

    Partition alignment places a partition's starting offset on boundaries appropriate to the storage topology reported by the underlying stack.

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  21. Term

    Partitioned filter

    An SST membership-filter layout split into independently loadable partitions located through a top-level index.

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  22. Term

    PATA

    Parallel ATA (PATA) is the original AT Attachment interface, in which a host reaches up to two disk drives per cable through a 40-pin connector that carries a compatible register set and a 16-bit parallel data bus, before serial ATA replaced it.

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  23. Term

    PCIe 4.0 storage

    PCIe 4.0 is the fourth generation of the PCI Express interconnect, signalling at 16 GT/s per lane with 128b/130b encoding (twice the rate of PCIe 3.0), which sets the link bandwidth available to PCIe-attached storage such as NVMe SSDs.

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  24. Term

    PCIe 5.0 storage

    PCIe 5.0 is the fifth generation of the PCI Express interface, running each lane at 32.0 GT/s with 128b/130b encoding, twice the per-lane rate of PCIe 4.0, which gives NVMe storage devices up to about 63 GB/s per direction on a x16 link and about 15.75 GB/s on the x4 link typical of an SSD (our calculation).

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  25. Term

    PCIe lanes (storage)

    A PCIe lane is one pair of transmit and receive signal paths between two PCI Express ports; a link bundles 1, 2, 4, 8 or 16 lanes, so the lane count (x1 to x16) together with the PCIe generation sets the peak bandwidth available to an SSD controller.

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  26. Term

    PCIe retimer

    A PCIe retimer is a physical-layer, protocol-aware and software-transparent extension device that fully recovers the data and clock of an incoming PCIe signal and retransmits a fresh copy, so one long channel becomes two separate, independently compliant electrical link segments; it is used where traces, connectors or cables would otherwise exceed the PCIe loss budget, for example in servers with many NVMe slots.

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  27. Term

    PCIe storage attachment

    Use of PCI Express lanes as the electrical transport for modern high-performance SSDs, usually with NVMe as the protocol.

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  28. Term

    Peering (Ceph)

    Ceph peering establishes agreement among OSDs about a placement group's object state and associated metadata.

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  29. Term

    Perpendicular magnetic recording (PMR)

    Perpendicular magnetic recording stores magnetization normal to the recording surface, independently of whether tracks overlap or writing is assisted.

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  30. Term

    Perpendicular magnetic tape

    Perpendicular magnetic tape is magnetic tape whose recording layer is magnetised perpendicular to the tape surface (as in perpendicular recording on disks), a medium that laboratory work has used to demonstrate areal densities of 148 to 201 Gb/in2.

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