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  2. Hard disk drive performance characteristics - Wikipedia

    en.wikipedia.org/wiki/Hard_disk_drive...

    A hard disk head on an access arm resting on a hard disk platter. The access time or response time of a rotating drive is a measure of the time it takes before the drive can actually transfer data. The factors that control this time on a rotating drive are mostly related to the mechanical nature of the rotating disks and moving heads. It is ...

  3. Access time - Wikipedia

    en.wikipedia.org/wiki/Access_time

    Access time is the time delay or latency between a request to an electronic system, and the access being initiated or the requested data returned.. In computer and software systems, it is the time interval between the point where an instruction control unit initiates a call to retrieve data or a request to store data, and the point at which delivery of the data is completed or the storage is ...

  4. Average memory access time - Wikipedia

    en.wikipedia.org/wiki/Average_memory_access_time

    AMAT's three parameters hit time (or hit latency), miss rate, and miss penalty provide a quick analysis of memory systems. Hit latency (H) is the time to hit in the cache. Miss rate (MR) is the frequency of cache misses, while average miss penalty (AMP) is the cost of a cache miss in terms of time. Concretely it can be defined as follows.

  5. IOPS - Wikipedia

    en.wikipedia.org/wiki/IOPS

    The specific number of IOPS possible in any system configuration will vary greatly, depending upon the variables the tester enters into the program, including the balance of read and write operations, the mix of sequential and random access patterns, the number of worker threads and queue depth, as well as the data block sizes. [1]

  6. Elevator algorithm - Wikipedia

    en.wikipedia.org/wiki/Elevator_algorithm

    The elevator algorithm, or SCAN, is a disk-scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests.. This algorithm is named after the behavior of a building elevator, where the elevator continues to travel in its current direction (up or down) until empty, stopping only to let individuals off or to pick up new individuals heading in the ...

  7. I/O scheduling - Wikipedia

    en.wikipedia.org/wiki/I/O_scheduling

    Shortest seek first, also known as Shortest Seek / Service Time First (SSTF) Elevator algorithm, also known as SCAN (including its variants, C-SCAN, LOOK, and C-LOOK) N-Step-SCAN SCAN of N records at a time; FSCAN, N-Step-SCAN where N equals queue size at start of the SCAN cycle; Budget Fair Queueing (BFQ) scheduler on Linux [2] [3]

  8. Hard disk drive - Wikipedia

    en.wikipedia.org/wiki/Hard_disk_drive

    Time to access data can be improved by increasing rotational speed (thus reducing latency) or by reducing the time spent seeking. Increasing areal density increases throughput by increasing data rate and by increasing the amount of data under a set of heads, thereby potentially reducing seek activity for a given amount of data. The time to ...

  9. Annualized failure rate - Wikipedia

    en.wikipedia.org/wiki/Annualized_failure_rate

    For example, AFR is used to characterize the reliability of hard disk drives.. The relationship between AFR and MTBF (in hours) is: [1] = (/) This equation assumes that the device or component is powered on for the full 8766 hours of a year, and gives the estimated fraction of an original sample of devices or components that will fail in one year, or, equivalently, 1 − AFR is the fraction of ...