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Commit 11373542 authored by NeilBrown's avatar NeilBrown
Browse files

Documentation/md.txt update 



Update md.txt to reflect recent changes in a number of sysfs
attributes.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent ec32a2bd

Documentation/md.txt

+30 −7
Original line number Diff line number Diff line
@@ -164,15 +164,19 @@ All md devices contain: 
  raid_disks

     a text file with a simple number indicating the number of devices

     in a fully functional array.  If this is not yet known, the file

     will be empty.  If an array is being resized (not currently

     possible) this will contain the larger of the old and new sizes.

     Some raid level (RAID1) allow this value to be set while the

     array is active.  This will reconfigure the array.   Otherwise

     it can only be set while assembling an array.

     will be empty.  If an array is being resized this will contain

     the new number of devices.

     Some raid levels allow this value to be set while the array is

     active.  This will reconfigure the array.   Otherwise it can only

     be set while assembling an array.

     A change to this attribute will not be permitted if it would

     reduce the size of the array.  To reduce the number of drives

     in an e.g. raid5, the array size must first be reduced by

     setting the 'array_size' attribute.



  chunk_size

     This is the size if bytes for 'chunks' and is only relevant to

     raid levels that involve striping (1,4,5,6,10). The address space

     This is the size in bytes for 'chunks' and is only relevant to

     raid levels that involve striping (0,4,5,6,10). The address space

     of the array is conceptually divided into chunks and consecutive

     chunks are striped onto neighbouring devices.

     The size should be at least PAGE_SIZE (4k) and should be a power
@@ -183,6 +187,20 @@ All md devices contain: 
     simply a number that is interpretted differently by different

     levels.  It can be written while assembling an array.



  array_size

     This can be used to artificially constrain the available space in

     the array to be less than is actually available on the combined

     devices.  Writing a number (in Kilobytes) which is less than

     the available size will set the size.  Any reconfiguration of the

     array (e.g. adding devices) will not cause the size to change.

     Writing the word 'default' will cause the effective size of the

     array to be whatever size is actually available based on

     'level', 'chunk_size' and 'component_size'.



     This can be used to reduce the size of the array before reducing

     the number of devices in a raid4/5/6, or to support external

     metadata formats which mandate such clipping.



  reshape_position

     This is either "none" or a sector number within the devices of

     the array where "reshape" is up to.  If this is set, the three
@@ -207,6 +225,11 @@ All md devices contain: 
     about the array.  It can be 0.90 (traditional format), 1.0, 1.1,

     1.2 (newer format in varying locations) or "none" indicating that

     the kernel isn't managing metadata at all.

     Alternately it can be "external:" followed by a string which

     is set by user-space.  This indicates that metadata is managed

     by a user-space program.  Any device failure or other event that

     requires a metadata update will cause array activity to be

     suspended until the event is acknowledged.



  resync_start

     The point at which resync should start.  If no resync is needed,