rebuilding raided root partition

[Miles Fidelman <mfidelman@traversetechnologies.com>]

Hi Folks,

I've been busily recovering from a bad crash (strangely enough, a single 
disk drive failure that brought down an entire raided environment, with 
spares).

I've pretty much recovered and rebuilt everything, EXCEPT....

my root partition is raided, and is now running only on its single spare 
drive:

-----
server1:~# more /proc/mdstat   
md2 : inactive sdd3[0] sdb3[2]
     195318016 blocks

server1:~# mdadm --detail /dev/md2  [details omitted]
/dev/md2:
    Raid Level : raid1
   Device Size : 97659008 (93.13 GiB 100.00 GB)
  Raid Devices : 2
 Total Devices : 2
Preferred Minor : 2
   Persistence : Superblock is persistent

        State : active, degraded
Active Devices : 0
Working Devices : 2
Failed Devices : 0
 Spare Devices : 2

   Number   Major   Minor   RaidDevice State
      0       8       51        0      spare rebuilding   /dev/sdd3
      1       0        0        -      removed

      2       8       19        -      spare   /dev/sdb3
------

note the line "spare rebuilding" - that's the result of: mdadm --add 
/dev/md2 /dev/sdd3
unfortunately, it doesn't seem to really be doing anything - it's been 
saying "rebuilding" for several hours

now for another mirror device, doing an mdadm --add, kicked off a resync 
(as indicated by cat /proc/mdstat) that concluded just fine with a 
rebuilt mirror array

but for this array, it just shows "active, degraged, and rebuilding" in 
mdadm --detail, and "inactive" in /proc/mdstat

about the only difference I can see, is that the array that rebuilt 
started with one primary drive, to which I added a 2nd drive, and then a 
spare; the one that's hanging is running on a spare, and it thinks I'm 
adding another spare  (note: both serve as physical volumes underlying LVM)

so..... on to questions:

1. What's going on?

2. Any suggestions on how to reassemble the array?  mdadm --assemble 
/dev/md2 tells me I need to deactivate the device, but then, it's my / 
volume - which leaves me a little stumped

Thanks very much,

Miles Fidelman





-- 
In theory, there is no difference between theory and practice.
In practice, there is.   .... Yogi Berra