p7 958 B

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  1. .SH
  2. Sync Copy and WORM Copy Processes
  3. .PP
  4. The
  5. .CW scp
  6. process
  7. wakes up every ten seconds and
  8. issues writes to blocks in the buffer cache
  9. that have been modified.
  10. This is done automatically on important
  11. console commands such as
  12. .CW halt
  13. and
  14. .CW dump .
  15. .PP
  16. The
  17. .CW wcp
  18. process also wakes up every ten seconds
  19. and tries to copy a
  20. .CW dump
  21. block from the cache to the WORM.
  22. As long as there are
  23. .CW dump
  24. blocks to copy and there is no competition for
  25. the WORM device,
  26. the copy will continue at full speed.
  27. Whenever there is competition for the WORM
  28. or there are no more blocks to
  29. copy,
  30. then the process will sleep ten seconds
  31. before looking again.
  32. .PP
  33. The HP WORM jukebox consists of
  34. 238 disks divided into 476 sides
  35. or platters.
  36. Platter 0 is the
  37. .I A
  38. side of disk 0.
  39. Platter 1 is the
  40. .I A
  41. side of the disk 1.
  42. Platter 238 is the
  43. .I B
  44. side of disk 0.
  45. On Emelie,
  46. the main file system is configured
  47. on both sides of the first 237 disks,
  48. platters 0-236 and 238-474.