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Diffstat (limited to 'Documentation/device-mapper/delay.txt')
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diff --git a/Documentation/device-mapper/delay.txt b/Documentation/device-mapper/delay.txt new file mode 100644 index 000000000..6426c4527 --- /dev/null +++ b/Documentation/device-mapper/delay.txt @@ -0,0 +1,28 @@ +dm-delay +======== + +Device-Mapper's "delay" target delays reads and/or writes +and maps them to different devices. + +Parameters: + <device> <offset> <delay> [<write_device> <write_offset> <write_delay> + [<flush_device> <flush_offset> <flush_delay>]] + +With separate write parameters, the first set is only used for reads. +Offsets are specified in sectors. +Delays are specified in milliseconds. + +Example scripts +=============== +[[ +#!/bin/sh +# Create device delaying rw operation for 500ms +echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed +]] + +[[ +#!/bin/sh +# Create device delaying only write operation for 500ms and +# splitting reads and writes to different devices $1 $2 +echo "0 `blockdev --getsz $1` delay $1 0 0 $2 0 500" | dmsetup create delayed +]] |