+ 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
+ of the array is conceptually divided into chunks and consecutive
+ chunks are striped onto neighbouring devices.
+ The size should be atleast PAGE_SIZE (4k) and should be a power
+ of 2. This can only be set while assembling an array
+
+ component_size
+ For arrays with data redundancy (i.e. not raid0, linear, faulty,
+ multipath), all components must be the same size - or at least
+ there must a size that they all provide space for. This is a key
+ part or the geometry of the array. It is measured in sectors
+ and can be read from here. Writing to this value may resize
+ the array if the personality supports it (raid1, raid5, raid6),
+ and if the component drives are large enough.
+
+ metadata_version
+ This indicates the format that is being used to record metadata
+ 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.
+
+ level
+ The raid 'level' for this array. The name will often (but not
+ always) be the same as the name of the module that implements the
+ level. To be auto-loaded the module must have an alias
+ md-$LEVEL e.g. md-raid5
+ This can be written only while the array is being assembled, not
+ after it is started.
+