[deliverable/linux.git] / Documentation / device-mapper / dm-flakey.txt

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.
Commit	Line	Data
3407ef52 JB	1	dm-flakey
	2	=========
	3
	4	This target is the same as the linear target except that it returns I/O
	5	errors periodically. It's been found useful in simulating failing
	6	devices for testing purposes.
	7
	8	Starting from the time the table is loaded, the device is available for
	9	<up interval> seconds, then returns errors for <down interval> seconds,
	10	and then this cycle repeats.
	11
	12	Parameters: <dev path> <offset> <up interval> <down interval>
	13	<dev path>: Full pathname to the underlying block-device, or a
	14	"major:minor" device-number.
	15	<offset>: Starting sector within the device.
	16	<up interval>: Number of seconds device is available.
	17	<down interval>: Number of seconds device returns errors.