5 Device-Mapper's "delay" target delays reads and/or writes
6 and/or flushs and optionally maps them to different devices.
10 <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
11 [<flush_device> <flush_offset> <flush_delay>]]
13 Table line has to either have 3, 6 or 9 arguments:
15 3: apply offset and delay to read, write and flush operations on device
17 6: apply offset and delay to device, also apply write_offset and write_delay
18 to write and flush operations on optionally different write_device with
19 optionally different sector offset
21 9: same as 6 arguments plus define flush_offset and flush_delay explicitely
22 on/with optionally different flush_device/flush_offset.
24 Offsets are specified in sectors.
26 Delays are specified in milliseconds.
35 # Create mapped device named "delayed" delaying read, write and flush operations for 500ms.
37 dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 500"
42 # Create mapped device delaying write and flush operations for 400ms and
43 # splitting reads to device $1 but writes and flushs to different device $2
44 # to different offsets of 2048 and 4096 sectors respectively.
46 dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 2048 0 $2 4096 400"
51 # Create mapped device delaying reads for 50ms, writes for 100ms and flushs for 333ms
52 # onto the same backing device at offset 0 sectors.
54 dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 50 $2 0 100 $1 0 333"