Re: Re-adding disks to RAID6 in a Fujitsu NAS: old mdadm?

[NeilBrown <neilb@suse.de>]

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On Tue, 26 Jun 2012 15:57:21 +0200 "Stefan G. Weichinger" <lists@xunil.at>
wrote:

> 
> Greets,
> 
> I currently try to re-add 2 disks to a RAID6 array.
> 
> There were 4 disks in a Fujitsu Q800 NAS, the RAID6 was done via WebGUI.
> 
> 2 disks have been removed from the array and I am not able to re-add the
> old disks or add new disks via WebGUI.
> 
> The support told me to "re-insert disks, if it doesn't work, rebuild
> array" ... cool. What do I need a RAID for then ??
> 
> Anway.
> 
> Entered hacking mode ;-) at least in my terms.
> 
> sshed into box.
> 
> To get it short:
> 
> Currently the RAID6 array /dev/md0 is:
> 
> md0 : active raid6 sdc3[2] sdd3[3]
>       3903891200 blocks level 6, 64k chunk, algorithm 2 [4/2] [__UU]
> 
> So I would like to re-add sda3 and sdb3 ...
> 
> I get:
> 
> # mdadm /dev/md0 -a /dev/sda3
> mdadm: /dev/sda3 not large enough to join array
> 
> oops!
> 
> But the comparison shows:
> 
> [~] # fdisk -l /dev/sda
> 
> Disk /dev/sda: 2000.3 GB, 2000398934016 bytes
> 255 heads, 63 sectors/track, 243201 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sda1               1          66      530125   83  Linux
> /dev/sda2              67         132      530142   83  Linux
> /dev/sda3             133      243138  1951945693   83  Linux
> /dev/sda4          243139      243200      498012   83  Linux
> 
> [~] # fdisk -l /dev/sdc
> 
> Disk /dev/sdc: 2000.3 GB, 2000398934016 bytes
> 255 heads, 63 sectors/track, 243201 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1               1          66      530125   83  Linux
> /dev/sdc2              67         132      530142   83  Linux
> /dev/sdc3             133      243138  1951945693   83  Linux
> /dev/sdc4          243139      243200      498012   83  Linux
> 
> -> identical partitions
> 
> ---
> 
> Could that relate to this issue:
> 
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=500309

Nope.  It was an earlier bug fixed in 2.6.5 by

 http://neil.brown.name/git?p=mdadm;a=commitdiff;h=7a3be72fc621b4a7589e923cf065


> 
> The NAS seems to run some ubuntu:
> 
> # cat /proc/version
> Linux version 2.6.33.2 (root@NasX86-5) (gcc version 4.1.3 20070929
> (prerelease) (Ubuntu 4.1.2-16ubuntu2)) #1 SMP Mon Sep 13 04:28:32 CST 2010

Does the "X86" in there suggest and x86 processor?  What does "uname -a" show?


> 
> and brings an older mdadm:
> 
> # mdadm --version
> mdadm - v2.6.3 - 20th August 2007
> 
> 
> If that is the issue, is there a way to use some newer binary (magically
> transferred to me by mail or URL ;-) ) of mdadm to re-add disks?

You mean the NAS didn't come with a complete build environment and sources
for all programs?  Outrageous.

If you have a machine with the same arch at the NAS, you could

  git clone git://neil.brown.name/mdadm -b mdadm-2.6.5
  cd mdadm
  make mdadm.static CWFLAGS=-Wall

and then use the "mdadm.static" on the NAS.

NeilBrown


> 
> I would really really like to avoid to rebuild that array ...
> 
> Thanks in advance, looking forward to your hints, Stefan!
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