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Everything about Count key data

Direct access storage device data recording format

Count key data (CKD) is a direct-access storage device (DASD) data recording format introduced in 1964, by IBM with its IBM System/360 and still being emulated on IBM mainframes. It is a self-defining format with each data record represented by a Count Area that identifies the record and provides the number of bytes in an optional Key Area and an optional Data Area. This is in contrast to devices using fixed sector size or a separate format track. Wikipedia →

🧭 Start here: a 6-step reading path

  1. Read the overview: Count key dataA 5-minute orientation
  2. Pick up a classic book: Loss ModelsThe most-reprinted book on the subject
  3. Read the landmark paper: A framework to identify key occupancy indicators for optimizing building operation using WiFi connection count dataCited 49 times
  4. Go sideways: History of IBM CKD ControllersA closely related topic
  5. Go sideways: Direct-access storage deviceA closely related topic

📖 Definitions

No dictionary entry for this exact phrase.

🗂️ The subject at a glance

  1. CKD track format
  2. IBM's CKD DASD subsystems
  3. Initial CKD feature set
  4. Block multiplexer channel enhancements
  5. Defect skipping
  6. Dynamic paths
  7. Nonsynchronous operation
  8. Caching
  9. Other extensions
  10. Beyond System/370

🏆 Landmark papers (most cited)

📚 Books worth reading

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