https://hesela.dev/Explicitly dated glossary revisions from the Hesela team.enhttps://hesela.dev/terms/adaptive-replica-selection/https://hesela.dev/terms/adaptive-replica-selection/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAdaptive replica selection routes a request among eligible data replicas using changing performance or load information rather than a fixed choice. https://hesela.dev/terms/afr/https://hesela.dev/terms/afr/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAnnualized failure rate (AFR) expresses observed failures relative to drive-time exposure, scaled to a year, and is not inherently a one-year failure probability. https://hesela.dev/terms/average-precision/https://hesela.dev/terms/average-precision/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTNon-interpolated average precision summarizes ranked prediction scores by weighting precision at each threshold by the corresponding increase in recall. https://hesela.dev/terms/backup-verification/https://hesela.dev/terms/backup-verification/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTBackup verification checks stored backup material against specified integrity and completeness rules. https://hesela.dev/terms/belady-anomaly/https://hesela.dev/terms/belady-anomaly/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA Belady anomaly occurs when a replacement policy produces more misses with a larger cache than with a smaller cache on the same reference string and initial-state convention. https://hesela.dev/terms/binomial-proportion/https://hesela.dev/terms/binomial-proportion/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA binomial proportion is an outcome count divided by a fixed number of independent binary trials, used to estimate their common outcome probability. https://hesela.dev/terms/bit-patterned-media/https://hesela.dev/terms/bit-patterned-media/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTBit-patterned media is a magnetic recording medium that stores individual bits on lithographically defined, separated magnetic islands. https://hesela.dev/terms/blocked-bloom-filter/https://hesela.dev/terms/blocked-bloom-filter/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA Bloom-filter layout that confines the bit probes for a key to one selected block to improve memory locality. https://hesela.dev/terms/bloom-filter/https://hesela.dev/terms/bloom-filter/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA compact approximate-membership structure that can reject absent keys but may report a false positive, without false negatives for correctly inserted keys in an intact standard filter. https://hesela.dev/terms/brier-score/https://hesela.dev/terms/brier-score/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTFor a binary event, the Brier score is the mean squared difference between each forecast probability and its observed zero-or-one outcome. https://hesela.dev/terms/buffered-io/https://hesela.dev/terms/buffered-io/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTBuffered I/O is file access through an operating-system cache, allowing transfers between an application and storage to be decoupled. https://hesela.dev/terms/cache-inclusion-property/https://hesela.dev/terms/cache-inclusion-property/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTThe cache inclusion property requires the resident set at a smaller capacity to be contained in that at a larger capacity after each shared request prefix under the same replacement policy. https://hesela.dev/terms/cache-pollution/https://hesela.dev/terms/cache-pollution/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTCache pollution occurs when low-reuse entries displace entries that would otherwise serve useful cache hits. https://hesela.dev/terms/charge-trap-flash/https://hesela.dev/terms/charge-trap-flash/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA flash cell design that stores charge in localized traps within an insulating material rather than on a conductive floating gate. https://hesela.dev/terms/clock-replacement/https://hesela.dev/terms/clock-replacement/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTCLOCK is a cache replacement policy that gives referenced entries another chance by clearing their reference state during an eviction scan. https://hesela.dev/terms/close/https://hesela.dev/terms/close/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTclose is an operation that releases a file descriptor so its number can be allocated again. https://hesela.dev/terms/confidence-interval/https://hesela.dev/terms/confidence-interval/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA confidence interval is a set of parameter values produced by a procedure with a stated repeated-sampling coverage under specified model and sampling assumptions. https://hesela.dev/terms/counting-bloom-filter/https://hesela.dev/terms/counting-bloom-filter/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA counting Bloom filter tracks approximate set membership with counters that support insertions and deletions through matched increments and decrements. https://hesela.dev/terms/crash-corruption-ambiguity/https://hesela.dev/terms/crash-corruption-ambiguity/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTCrash-corruption ambiguity occurs when the same observed stored state is consistent with both an interrupted update and corruption after persistence. https://hesela.dev/terms/cuckoo-filter/https://hesela.dev/terms/cuckoo-filter/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA cuckoo filter is an approximate-membership structure that stores short fingerprints in candidate buckets and supports insertion, lookup and deletion subject to its update contract. https://hesela.dev/terms/data-scrubbing/https://hesela.dev/terms/data-scrubbing/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTData scrubbing is proactive verification of stored data to discover errors before ordinary access requires the affected content. https://hesela.dev/terms/drive-day/https://hesela.dev/terms/drive-day/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA drive-day is one drive observed in operation for one day, used as a unit of fleet exposure. https://hesela.dev/terms/dwpd/https://hesela.dev/terms/dwpd/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTDWPD is an SSD endurance rating that normalizes cumulative host writes by host-addressable drive capacity and the number of days in a specified period. https://hesela.dev/terms/emmc/https://hesela.dev/terms/emmc/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTeMMC is a JEDEC-standard managed-flash device that combines NAND memory and a controller in one package and communicates through a parallel MMC interface. https://hesela.dev/terms/expected-calibration-error/https://hesela.dev/terms/expected-calibration-error/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTExpected calibration error is a summary of disagreement between predicted probabilities and conditional outcome frequencies, commonly estimated by bin-weighted gaps on an evaluation sample. https://hesela.dev/terms/f1-score/https://hesela.dev/terms/f1-score/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTF1 score is the harmonic mean of precision and recall for a specified positive class and decision threshold. https://hesela.dev/terms/failure-detector/https://hesela.dev/terms/failure-detector/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA failure detector is a component that uses observations to report whether another process or endpoint is suspected of being unavailable. https://hesela.dev/terms/file-descriptor/https://hesela.dev/terms/file-descriptor/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA file descriptor is a nonnegative integer used by a process to refer to an open file description for operations such as reading, writing or closing. https://hesela.dev/terms/file-truncation/https://hesela.dev/terms/file-truncation/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTFile truncation changes a regular file to a specified byte length, discarding data beyond a shorter end or extending it when supported. https://hesela.dev/terms/fifo-replacement/https://hesela.dev/terms/fifo-replacement/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTFirst-in first-out cache replacement evicts the resident entry that was inserted earliest, without refreshing its queue position on a hit. https://hesela.dev/terms/data-retention/https://hesela.dev/terms/data-retention/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTFlash data retention is the ability of programmed NAND data to remain recoverable over time without refresh under specified wear, storage and read conditions. https://hesela.dev/terms/fsync/https://hesela.dev/terms/fsync/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTfsync is a file-synchronization operation that requests persistence of a file's modified data and associated metadata before reporting completion. https://hesela.dev/terms/full-page-write/https://hesela.dev/terms/full-page-write/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA PostgreSQL full-page write records a recoverable page image in WAL to support recovery from an incomplete data-page write. https://hesela.dev/terms/hard-link/https://hesela.dev/terms/hard-link/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA hard link is a directory entry naming an existing file's inode, so multiple hard links refer to the same file rather than to separate copies. https://hesela.dev/terms/hamr/https://hesela.dev/terms/hamr/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTHeat-assisted magnetic recording uses localized optical heating to enable magnetic writing of high-anisotropy HDD media. https://hesela.dev/terms/hedged-request/https://hesela.dev/terms/hedged-request/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTA hedged request is a redundant copy dispatched after an initial request remains unfinished for a chosen delay, allowing an eligible response to complete the operation. https://hesela.dev/terms/inspection-paradox/https://hesela.dev/terms/inspection-paradox/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTThe inspection paradox is the length bias by which sampling a time point overrepresents long intervals compared with sampling intervals equally. https://hesela.dev/terms/interarrival-time/https://hesela.dev/terms/interarrival-time/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn interarrival time is the elapsed interval between consecutive events in a specified event stream. https://hesela.dev/terms/io-uring/https://hesela.dev/terms/io-uring/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTio_uring is a Linux asynchronous I/O interface that exchanges requests and completion results through shared submission and completion rings. https://hesela.dev/terms/io-uring-cancellation/https://hesela.dev/terms/io-uring-cancellation/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTio_uring cancellation is a request to stop matching outstanding operations, with a result separate from each target operation's completion. https://hesela.dev/terms/io-uring-linked-requests/https://hesela.dev/terms/io-uring-linked-requests/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTio_uring linked requests are a chain of submission entries whose dependencies delay each successor until its predecessor completes. https://hesela.dev/terms/io-uring-linked-timeout/https://hesela.dev/terms/io-uring-linked-timeout/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn io_uring linked timeout is a timer request attached to an operation that can trigger cancellation when its deadline expires. https://hesela.dev/terms/iscsi/https://hesela.dev/terms/iscsi/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTiSCSI is a storage transport protocol that carries SCSI commands, data and responses between initiators and targets over TCP/IP networks. https://hesela.dev/terms/iscsi-cmdsn/https://hesela.dev/terms/iscsi-cmdsn/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn iSCSI Command Sequence Number (CmdSN) identifies a command's position in the session-wide delivery sequence. https://hesela.dev/terms/iscsi-connection/https://hesela.dev/terms/iscsi-connection/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn iSCSI connection is a TCP connection carrying iSCSI protocol messages between an initiator and a target within an iSCSI session. https://hesela.dev/terms/iscsi-error-recovery-level/https://hesela.dev/terms/iscsi-error-recovery-level/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTThe iSCSI Error Recovery Level is the session-wide negotiated value from 0 to 2 that selects the protocol recovery capabilities available to an initiator and target. https://hesela.dev/terms/iscsi-network-portal/https://hesela.dev/terms/iscsi-network-portal/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn iSCSI network portal is a TCP/IP access point used by an iSCSI node, identified by an IP address at an initiator and by an IP address plus listening TCP port at a target. https://hesela.dev/terms/iscsi-node-name/https://hesela.dev/terms/iscsi-node-name/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn iSCSI node name is the persistent, location-independent identifier of an iSCSI initiator or target, distinct from the IP addresses through which that node is reached. https://hesela.dev/terms/iscsi-portal-group/https://hesela.dev/terms/iscsi-portal-group/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn iSCSI portal group is a node-scoped set of network portals capable of coordinating the connections of a common iSCSI session. https://hesela.dev/terms/iscsi-session/https://hesela.dev/terms/iscsi-session/#updated-2026-10-17Sat, 17 Oct 2026 00:00:00 GMTAn iSCSI session is a protocol association between an initiator and a target that groups TCP connections and, for a normal session, represents a SCSI I_T nexus.