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The DM support describes lots of aspects related to mapped disk partitions from the userspace PoV. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
32 lines
795 B
ReStructuredText
32 lines
795 B
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========
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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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[<flush_device> <flush_offset> <flush_delay>]]
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With separate write parameters, the first set is only used for reads.
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Offsets are specified in sectors.
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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 --getsz $1` delay $1 0 500" | dmsetup create delayed
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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 --getsz $1` delay $1 0 0 $2 0 500" | dmsetup create delayed
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