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1========2dm-delay3========4 5Device-Mapper's "delay" target delays reads and/or writes6and/or flushs and optionally maps them to different devices.7 8Arguments::9 10 <device> <offset> <delay> [<write_device> <write_offset> <write_delay>11 [<flush_device> <flush_offset> <flush_delay>]]12 13Table line has to either have 3, 6 or 9 arguments:14 153: apply offset and delay to read, write and flush operations on device16 176: apply offset and delay to device, also apply write_offset and write_delay18 to write and flush operations on optionally different write_device with19 optionally different sector offset20 219: same as 6 arguments plus define flush_offset and flush_delay explicitely22 on/with optionally different flush_device/flush_offset.23 24Offsets are specified in sectors.25 26Delays are specified in milliseconds.27 28 29Example scripts30===============31 32::33 #!/bin/sh34 #35 # Create mapped device named "delayed" delaying read, write and flush operations for 500ms.36 #37 dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 500"38 39::40 #!/bin/sh41 #42 # Create mapped device delaying write and flush operations for 400ms and43 # splitting reads to device $1 but writes and flushs to different device $244 # to different offsets of 2048 and 4096 sectors respectively.45 #46 dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 2048 0 $2 4096 400"47 48::49 #!/bin/sh50 #51 # Create mapped device delaying reads for 50ms, writes for 100ms and flushs for 333ms52 # onto the same backing device at offset 0 sectors.53 #54 dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 50 $2 0 100 $1 0 333"55