[Devil-linux-develop] [ devil-linux-Feature Requests-515935 ] add mdctl (raid tools)

[<no...@so...>]

Feature Requests item #515935, was opened at 2002-02-11 06:57
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=410646&aid=515935&group_id=34096

Category: Packages
Group: None
Status: Open
Priority: 5
Submitted By: Heiko Zuerker (smiley73)
Assigned to: Nobody/Anonymous (nobody)
Summary: add mdctl (raid tools)

Initial Comment:

BETTER use mdctl!

-------- Original Message --------
Subject: ANNOUNCE: mdctl 0.5 available
Date: Thu, 23 Aug 2001 14:04:36 +1000 (EST)
From: Neil Brown <ne...@cs...>
To: lin...@vg...


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 <da...@ag...>.
  
  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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