delay.rst 795 B

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  1. ========
  2. dm-delay
  3. ========
  4. Device-Mapper's "delay" target delays reads and/or writes
  5. and maps them to different devices.
  6. Parameters::
  7. <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
  8. [<flush_device> <flush_offset> <flush_delay>]]
  9. With separate write parameters, the first set is only used for reads.
  10. Offsets are specified in sectors.
  11. Delays are specified in milliseconds.
  12. Example scripts
  13. ===============
  14. ::
  15. #!/bin/sh
  16. # Create device delaying rw operation for 500ms
  17. echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
  18. ::
  19. #!/bin/sh
  20. # Create device delaying only write operation for 500ms and
  21. # splitting reads and writes to different devices $1 $2
  22. echo "0 `blockdev --getsz $1` delay $1 0 0 $2 0 500" | dmsetup create delayed