From:	 Neil Brown <neilb@cse.unsw.edu.au>
To:	 linux-raid@vger.kernel.org
Subject: ANNOUNCE: mdctl 0.5 available
Date:	 Thu, 23 Aug 2001 14:04:36 +1000 (EST)


I would like to announce the availablilty of mdctl-0.5 from

  http://www.cse.unsw.edu.au/~neilb/source/mdctl/

Note:
  it is expected that the name will change when 1.0 comes out,
  probably to mdadmin (it is easier to pronounce)

Changes:
  --assemble:
     spare drives are handled properly.

     --force can be used to recover from 2-drive failures on RAID5
     If you belive that /dev/hda1 /dev/hdb1 /dev/hdc1 /dev/hdd1 should
     make a raid5 array, but it has experienced multiple failures and
     wont start, then

       mdctl --assemble --force /dev/md0 /dev/hd[abcd]1

     Should update the superblock on the newest failed drive and
     restart the array in degraded mode.  You should then remove the
     remaining failed drive and re-add it (if you are happy that it
     might work).

     Ofcourse whenever you have a 2-drive failure, you have a risk
     of corruption in data that hasn't be changed for a long time.  So
     this doesn't give you your array back all nice and happy, but it
     does allow you to recover data that might not be corrupt.

     More flexibility in identifying a RAID array in the mdctl.conf
     e.g.
         array /dev/md4  super-minor=4

      assembles /dev/md4 from all devices found that have a raid
      superblock that says the minor number of the array is 4.
      If the blocks with the right minor number do not all have the
      same UUID, an error is flags and no assembly happens.
 
        array /dev/md3  devices=/dev/hd[abc]2

      Assembles /dev/md3 drom /dev/hda2 /dev/hdb2 and/dev/hdc2.  All
      devices must exist and have raid superblock with the same uuid.

      If two identity specifiers are used, only devices that match all
      of them are considered, so

        array /dev/md2 devices=/dev/hd?2 super-minor=2

      will assemble /dev/md2 using all /dev/hd?2 devices which have a 
      raid superblock with minor number 2.
 
  --create:
      When listing devices for --create, the word "missing" can be
      used to indicate that the respective slot does not have a
      working drive currently.  This is similar to the "failed-disk"
      directive in mkraid/raidtab.
      e.g.
         mdctl --create --level=5 -raid-disks=4 --spare-disks=2
                 /dev/md0 /dev/sda /dev/sdb missing /dev/sdc /dev/sdd  /dev/sde

      will create a raid5 array with the third slot empty, and two
      spares.

      By default, raid5 arrays are created with the last slot empty
      and drive listed for the last slot added as a spare.  If a
      "missing" slot is given, or if --force is given, then --create
      does exactly what you ask and doesn't try to be clever.
   

   --follow / --monitor:

      This is a new mode.  I couldn't stop my self from picking a name
      starting with F (as current modes start A,B,C,D,E) but I
      relented and provided an alternate name that is somewhat more
      meaningful. 
 
      In this mode, mdctl does not exit, but runs continuously and
      periodically polls all the md devices to see if they have had
      any interested state change.
      The changes that it currently notices are:
           Fail      -  an active disc fails
           FailSpare -  a spare, that was presumably being build, fails
           ActiveSpare - a spare becomes active, presumably after a rebuild.

      Options:
         --mail mailaddress  - send Email on any Fail* event
         --program program   - run the program on any event.  
		   Args are: eventname mddevice subdevice(if-known)
         --delay  seconds    - change from the default 60second pause
			       between polls.

      I plan to add functionality to this mode to allow sharing of
      spare drives. If an array is marks "spare-group=fred", and it
      has a failed drive and no spares, and if some other array is
      also "spare-group=fred" and it has no failed drives, but does
      have a spare drive that is big enough, the spare will be moved
      to the first array.

  I also have the idea of adding a --grow mode which will re-organise
  the data on an N disk raid0/4/5 array to be on an N+M disk array.
  I have no concrete plans for this though.

  I got rid of the "v" in the archive file name, and include the
  version number in the directory created by the archive.

  There is now a man page and mdctl.spec (for rpm) thanks to
  Danilo Godec <danci@agenda.si>.
  
  Ofcourse, the man page is now out of date and despite being based on
  the --help output, is not wholy correct.  After I get --follow
  working properly, I plan to revise the various documentation and/or
  the code to make sure the two match.

NeilBrown
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