aboutsummaryrefslogtreecommitdiff
path: root/Documentation/md.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/md.txt')
-rw-r--r--Documentation/md.txt67
1 files changed, 67 insertions, 0 deletions
diff --git a/Documentation/md.txt b/Documentation/md.txt
index 03a13c462cf..0668f9dc9d2 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -200,6 +200,17 @@ All md devices contain:
This can be written only while the array is being assembled, not
after it is started.
+ layout
+ The "layout" for the array for the particular level. This is
+ simply a number that is interpretted differently by different
+ levels. It can be written while assembling an array.
+
+ resync_start
+ The point at which resync should start. If no resync is needed,
+ this will be a very large number. At array creation it will
+ default to 0, though starting the array as 'clean' will
+ set it much larger.
+
new_dev
This file can be written but not read. The value written should
be a block device number as major:minor. e.g. 8:0
@@ -207,6 +218,54 @@ All md devices contain:
available. It will then appear at md/dev-XXX (depending on the
name of the device) and further configuration is then possible.
+ safe_mode_delay
+ When an md array has seen no write requests for a certain period
+ of time, it will be marked as 'clean'. When another write
+ request arrive, the array is marked as 'dirty' before the write
+ commenses. This is known as 'safe_mode'.
+ The 'certain period' is controlled by this file which stores the
+ period as a number of seconds. The default is 200msec (0.200).
+ Writing a value of 0 disables safemode.
+
+ array_state
+ This file contains a single word which describes the current
+ state of the array. In many cases, the state can be set by
+ writing the word for the desired state, however some states
+ cannot be explicitly set, and some transitions are not allowed.
+
+ clear
+ No devices, no size, no level
+ Writing is equivalent to STOP_ARRAY ioctl
+ inactive
+ May have some settings, but array is not active
+ all IO results in error
+ When written, doesn't tear down array, but just stops it
+ suspended (not supported yet)
+ All IO requests will block. The array can be reconfigured.
+ Writing this, if accepted, will block until array is quiessent
+ readonly
+ no resync can happen. no superblocks get written.
+ write requests fail
+ read-auto
+ like readonly, but behaves like 'clean' on a write request.
+
+ clean - no pending writes, but otherwise active.
+ When written to inactive array, starts without resync
+ If a write request arrives then
+ if metadata is known, mark 'dirty' and switch to 'active'.
+ if not known, block and switch to write-pending
+ If written to an active array that has pending writes, then fails.
+ active
+ fully active: IO and resync can be happening.
+ When written to inactive array, starts with resync
+
+ write-pending
+ clean, but writes are blocked waiting for 'active' to be written.
+
+ active-idle
+ like active, but no writes have been seen for a while (safe_mode_delay).
+
+
sync_speed_min
sync_speed_max
This are similar to /proc/sys/dev/raid/speed_limit_{min,max}
@@ -250,10 +309,18 @@ Each directory contains:
faulty - device has been kicked from active use due to
a detected fault
in_sync - device is a fully in-sync member of the array
+ writemostly - device will only be subject to read
+ requests if there are no other options.
+ This applies only to raid1 arrays.
spare - device is working, but not a full member.
This includes spares that are in the process
of being recoverred to
This list make grow in future.
+ This can be written to.
+ Writing "faulty" simulates a failure on the device.
+ Writing "remove" removes the device from the array.
+ Writing "writemostly" sets the writemostly flag.
+ Writing "-writemostly" clears the writemostly flag.
errors
An approximate count of read errors that have been detected on