From 26b9f228703f0518a90e7513d6fe7b6abeed5138 Mon Sep 17 00:00:00 2001 From: Heinz Mauelshagen Date: Wed, 9 May 2007 02:33:06 -0700 Subject: dm: delay target New device-mapper target that can delay I/O (for testing). Reads can be separated from writes, redirected to different underlying devices and delayed by differing amounts of time. Signed-off-by: Heinz Mauelshagen Signed-off-by: Milan Broz Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/device-mapper/delay.txt | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 Documentation/device-mapper/delay.txt (limited to 'Documentation/device-mapper') diff --git a/Documentation/device-mapper/delay.txt b/Documentation/device-mapper/delay.txt new file mode 100644 index 00000000000..15adc55359e --- /dev/null +++ b/Documentation/device-mapper/delay.txt @@ -0,0 +1,26 @@ +dm-delay +======== + +Device-Mapper's "delay" target delays reads and/or writes +and maps them to different devices. + +Parameters: + [ ] + +With separate write parameters, the first set is only used for reads. +Delays are specified in milliseconds. + +Example scripts +=============== +[[ +#!/bin/sh +# Create device delaying rw operation for 500ms +echo "0 `blockdev --getsize $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 --getsize $1` delay $1 0 0 $2 0 500" | dmsetup create delayed +]] -- cgit v1.2.3-18-g5258