mdadm --examine displays something different than --detail

Question

Who should I trust to fill my /etc/mdadm/mdadm.conf ? mdadm --examine --scan returns /dev/md/0 while obviously it's /dev/md0 that is currently rebuilding

What should I put in my /etc/mdadm/mdadm.conf ?

ARRAY /dev/md0 metadata=1.2 UUID=e7c87d29:37d0d6b4:9a336d4f:0e239a13 name=bigbenn:0

or

ARRAY /dev/md/0 metadata=1.2 UUID=e7c87d29:37d0d6b4:9a336d4f:0e239a13 name=bigbenn:0

➜  ~  sudo mdadm --detail /dev/md0
[sudo] password for lotso: 
/dev/md0:
    Version : 1.2
  Creation Time : Tue Nov  6 15:41:25 2012
     Raid Level : raid5
     Array Size : 7813527552 (7451.56 GiB 8001.05 GB)
  Used Dev Size : 1953381888 (1862.89 GiB 2000.26 GB)
   Raid Devices : 5
  Total Devices : 5
    Persistence : Superblock is persistent

    Update Time : Sun Dec 14 22:05:35 2014
      State : clean, degraded, recovering 
 Active Devices : 4
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 1

     Layout : left-symmetric
     Chunk Size : 512K

 Rebuild Status : 84% complete

       Name : bigbenn:0  (local to host bigbenn)
       UUID : e7c87d29:37d0d6b4:9a336d4f:0e239a13
     Events : 188171

    Number   Major   Minor   RaidDevice State
       6       8       33        0      spare rebuilding   /dev/sdc1
       7       8       81        1      active sync   /dev/sdf1
       5       8       97        2      active sync   /dev/sdg1
       4       8        1        3      active sync   /dev/sda1
       8       8       49        4      active sync   /dev/sdd1
➜  ~  sudo mdadm --examine --scan 
ARRAY /dev/md/0  metadata=1.2 UUID=e7c87d29:37d0d6b4:9a336d4f:0e239a13 name=bigbenn:0

Answer 1

$ ls -l /dev/md
total 0
lrwxrwxrwx 1 root root 6 Apr  5  2014 0 -> ../md0
lrwxrwxrwx 1 root root 6 Apr  5  2014 1 -> ../md1
lrwxrwxrwx 1 root root 6 Aug 11 14:20 2 -> ../md2

As you can see, the /dev/md/0 entry is simply a symlink to /dev/md0.

It seems that the mdadm software prefers the /dev/md/0 form, so I'd go with that. Both should work.