Re: RAID1 with multiple partitions

[Bob Proulx]

Tom H wrote:
> Both "mdadm --detail /dev/mdX" and "mdadm --examine /dev/sdXY" will
> output "(local to host <hostname>)" on the uuid line for metadata
> v0.90 and on the name line for metadata v1.x.

I never see that[1] and therefore conclude that if HOMEHOST is never
set in the configuration file that it will not set it in the
superblock.  (Because I don't set it and I don't see it while you do
set it and you do see it.)

> When you refer to "/dev/mdX_Y", do you mean partitionable arrays
> (/dev/md/dX", "/dev/md/dXpY")?

I was referring to this part of the documentation:

              When arrays are assembled using auto-assembly, arrays
              which do not record the correct homehost name in their
              metadata will be assembled using a "foreign" name.  A
              "foreign" name alway ends with a digit string preceded
              by an underscore to differentiate it from any possible
              local name. e.g.  /dev/md/1_1 or /dev/md/home_0.

Bob

[1] Here is an example of output from one of my systems.

$ sudo mdadm --detail /dev/md3
/dev/md3:
        Version : 0.90
  Creation Time : Fri Apr 30 17:21:44 2010
     Raid Level : raid1
     Array Size : 419625728 (400.19 GiB 429.70 GB)
  Used Dev Size : 419625728 (400.19 GiB 429.70 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 3
    Persistence : Superblock is persistent

    Update Time : Thu Dec 16 23:12:50 2010
          State : active
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : 92ad3585:f8512ceb:e680833b:09bbf4f8
         Events : 0.389969

    Number   Major   Minor   RaidDevice State
       0       8        7        0      active sync   /dev/sda7
       1       8       23        1      active sync   /dev/sdb7

$ sudo mdadm --examine /dev/sda7
/dev/sda7:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : 92ad3585:f8512ceb:e680833b:09bbf4f8
  Creation Time : Fri Apr 30 17:21:44 2010
     Raid Level : raid1
  Used Dev Size : 419625728 (400.19 GiB 429.70 GB)
     Array Size : 419625728 (400.19 GiB 429.70 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 3

    Update Time : Thu Dec 16 23:14:04 2010
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0
       Checksum : e382b3ce - correct
         Events : 389968


      Number   Major   Minor   RaidDevice State
this     0       8        7        0      active sync   /dev/sda7

   0     0       8        7        0      active sync   /dev/sda7
   1     1       8       23        1      active sync   /dev/sdb7

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