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f0ba4377 | 1 | ======== |
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2 | dm-delay |
3 | ======== | |
4 | ||
5 | Device-Mapper's "delay" target delays reads and/or writes | |
6 | and maps them to different devices. | |
7 | ||
f0ba4377 MCC |
8 | Parameters:: |
9 | ||
cda6b5ab MP |
10 | <device> <offset> <delay> [<write_device> <write_offset> <write_delay> |
11 | [<flush_device> <flush_offset> <flush_delay>]] | |
26b9f228 HM |
12 | |
13 | With separate write parameters, the first set is only used for reads. | |
f49e869a | 14 | Offsets are specified in sectors. |
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15 | Delays are specified in milliseconds. |
16 | ||
17 | Example scripts | |
18 | =============== | |
f0ba4377 MCC |
19 | |
20 | :: | |
21 | ||
22 | #!/bin/sh | |
23 | # Create device delaying rw operation for 500ms | |
24 | echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed | |
25 | ||
26 | :: | |
27 | ||
28 | #!/bin/sh | |
29 | # Create device delaying only write operation for 500ms and | |
30 | # splitting reads and writes to different devices $1 $2 | |
31 | echo "0 `blockdev --getsz $1` delay $1 0 0 $2 0 500" | dmsetup create delayed |