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author | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-06-18 18:40:23 +0300 |
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committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-07-15 17:03:01 +0300 |
commit | 6cf2a73cb2bc422a03984b285a63632c27f8c4e4 (patch) | |
tree | cb508e0a180ce350a86842353c5cb417e560835b /Documentation/admin-guide/device-mapper/delay.rst | |
parent | 159a5e78bdcabb1f87ee5536182a99a307ae0bac (diff) | |
download | linux-6cf2a73cb2bc422a03984b285a63632c27f8c4e4.tar.xz |
docs: device-mapper: move it to the admin-guide
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>
Diffstat (limited to 'Documentation/admin-guide/device-mapper/delay.rst')
-rw-r--r-- | Documentation/admin-guide/device-mapper/delay.rst | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/admin-guide/device-mapper/delay.rst b/Documentation/admin-guide/device-mapper/delay.rst new file mode 100644 index 000000000000..917ba8c33359 --- /dev/null +++ b/Documentation/admin-guide/device-mapper/delay.rst @@ -0,0 +1,31 @@ +======== +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 |