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Free Files and disks lessonsFiles and disks · Stage 1 · Disks · Step 1

How long a disk access takes

Break a hard-disk read into seek, rotation and transfer, and see why positioning dominates small reads. About 12 minutes.

Quick check

For a small random read on a hard disk, which part of the access time is usually the largest?

  1. ASeek time and rotational latency (positioning)
  2. BTransfer time
  3. CCPU time in the driver
Show the answer

Seek time and rotational latency (positioning). Milliseconds, against fractions of a millisecond for the transfer.

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