aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/device-mapper
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/device-mapper')
-rw-r--r--Documentation/device-mapper/delay.txt26
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/device-mapper/delay.txt b/Documentation/device-mapper/delay.txt
new file mode 100644
index 0000000..15adc55
--- /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:
+ <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
+
+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
+]]