Merge to Fedora kernel-2.6.18-1.2224_FC5 patched with stable patch-2.6.18.1-vs2.0...

[linux-2.6.git] / Documentation / md.txt

diff --git a/Documentation/md.txt b/Documentation/md.txt
index 03a13c4..0668f9d 100644 (file)
--- 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.
 
      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
    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.
 
      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}
    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
              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.
              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
 
       errors
        An approximate count of read errors that have been detected on