Documentation/device-mapper/delay.txt

   1 dm-delay
   2 ========
   3
   4 Device-Mapper's "delay" target delays reads and/or writes
   5 and maps them to different devices.
   6
   7 Parameters:
   8     <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
   9
  10 With separate write parameters, the first set is only used for reads.
  11 Delays are specified in milliseconds.
  12
  13 Example scripts
  14 ===============
  15 [[
  16 #!/bin/sh
  17 # Create device delaying rw operation for 500ms
  18 echo "0 `blockdev --getsize $1` delay $1 0 500" | dmsetup create delayed
  19 ]]
  20
  21 [[
  22 #!/bin/sh
  23 # Create device delaying only write operation for 500ms and
  24 # splitting reads and writes to different devices $1 $2
  25 echo "0 `blockdev --getsize $1` delay $1 0 0 $2 0 500" | dmsetup create delayed
  26 ]]