From 3407ef5262b55ca5d7139d2b555ef792fe531eec Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Thu, 24 Mar 2011 13:54:24 +0000
Subject: dm: add flakey target

This target is the same as the linear target except that it returns I/O
errors periodically.  It's been found useful in simulating failing
devices for testing purposes.

I needed a dm target to do some failure testing on btrfs's raid code, and
Mike pointed me at this.

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
 Documentation/device-mapper/dm-flakey.txt | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 Documentation/device-mapper/dm-flakey.txt

(limited to 'Documentation')

diff --git a/Documentation/device-mapper/dm-flakey.txt b/Documentation/device-mapper/dm-flakey.txt
new file mode 100644
index 000000000000..c8efdfd19a65
--- /dev/null
+++ b/Documentation/device-mapper/dm-flakey.txt
@@ -0,0 +1,17 @@
+dm-flakey
+=========
+
+This target is the same as the linear target except that it returns I/O
+errors periodically.  It's been found useful in simulating failing
+devices for testing purposes.
+
+Starting from the time the table is loaded, the device is available for
+<up interval> seconds, then returns errors for <down interval> seconds,
+and then this cycle repeats.
+
+Parameters: <dev path> <offset> <up interval> <down interval>
+    <dev path>: Full pathname to the underlying block-device, or a
+                "major:minor" device-number.
+    <offset>: Starting sector within the device.
+    <up interval>: Number of seconds device is available.
+    <down interval>: Number of seconds device returns errors.
-- 
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