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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 <mauelshagen@redhat.com> Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
26 lines
694 B
Text
26 lines
694 B
Text
dm-delay
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========
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Device-Mapper's "delay" target delays reads and/or writes
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and maps them to different devices.
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Parameters:
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<device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
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With separate write parameters, the first set is only used for reads.
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Delays are specified in milliseconds.
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Example scripts
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===============
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[[
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#!/bin/sh
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# Create device delaying rw operation for 500ms
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echo "0 `blockdev --getsize $1` delay $1 0 500" | dmsetup create delayed
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]]
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[[
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#!/bin/sh
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# Create device delaying only write operation for 500ms and
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# splitting reads and writes to different devices $1 $2
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echo "0 `blockdev --getsize $1` delay $1 0 0 $2 0 500" | dmsetup create delayed
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]]
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