Re: "mdadm -Dsv" output

On Tue, 29 Jun 2010 16:39:47 -0700 (PDT)
Adrian Sandor [off-list ref] wrote:

Well, I figured out a few things after spending some time with the mdadm man page:
- the "_0" suffix is possibly related to the "homehost" (I guess the computer's hostname was modified) and auto-assembly; I have both "n" and "n_0" symlinks in /dev/md on those machines, pointing to the same "/dev/mdn" devices
- I can use /proc/mdstat for info instead; it looks decent, uses "mdn" names, can be accessed as a normal user, and doesn't require mdadm
- there's also /proc/partitions - very nifty

Still, I would like the output of mdadm -Dsv to be improved (regarding formatting and consistency).

Thanks for your comments.

The missing space before "level" is fixed in newer versions of mdadm.

The variability in the array name (/dev/md0 vs /dev/md/0 vs /dev/md/0_0) does
appear clumsy I agree.
The name should be the name that was used to assemble the array.  If mdadm
was asked to choose a name automatically it will do the best it case, which
is different depending on the style of metadata used.

With the original 0.90 metadata, the array only knows a number that can
identify it, so you get /dev/mdNN - e.g. /dev/md0
With 1.x metadata, the array knows a name, so you get /dev/md/XXXX, e.g.
  /dev/md/0 or /dev/md/home
depending on what name was used to create it.

If the array appears to come from a different host, then mdadm appends a _NN
suffix to ensure the name doesn't conflict with the name of a local array.

NeilBrown