CentOS - May 2005 - Software RAID on Centos 4 - new issue

OK, I have managed to get software RAID 1 running on my wonderful Proliant
server but now have two challenges:

1) Fresh after an OS install and reboot, the RAID array starts to do its
stuff but straight away (as part of the boot messages) I am told that the
second disk is 'not ready for command' and the system hangs as soon as
resyncing starts. I think this is fixed by adding an hdparm line to turn on
DMA (I was also losing ticks), but cannot check this because...

2) As part of the testing, I rebooted the system with the second drive
pulled out, the whole lot then boots and I can use mdadm -a to add the
second drive to the mirrored pair. The drives resync at a decent speed and
the pair works fine for the duration, but when I reboot the second drive is
not part of the mirrored pair unless I manually add it again.

Looking at the md superblock for the second disk, I am wondering if all the
attempts at setting up the RAID array have confused it as this is what I get
- the last section looks wrong (??) 

 mdadm -E /dev/hde
/dev/hde:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : b0dcd24f:7044414a:1f0ba458:adabce9e
  Creation Time : Thu Sep 16 06:21:59 2004
     Raid Level : raid1
    Device Size : 193157440 (184.21 GiB 197.79 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0

    Update Time : Wed May 11 09:13:50 2005
          State : clean
 Active Devices : 1
Working Devices : 2
 Failed Devices : 1
  Spare Devices : 1
       Checksum : 2652883e - correct
         Events : 0.15217


      Number   Major   Minor   RaidDevice State
this     2      33        0        2      spare   /dev/hde
   0     0      22        3        0      active sync   /dev/hdc3
   1     1       0        0        1      faulty removed
   2     2      33        0        2      spare   /dev/hde


Any suggestions on getting this pair talking properly?

Thanks

Nigel

I had similar problems when I tried to use whole discs e.g. /dev/hde.
Solution was to use partiotion (one for whole disc) = /dev/hde1
with type 0xfd.
-- 
Sincerely
Ivo Panacek

Nigel Kendrick wrote:
> 2) As part of the testing, I rebooted the system with the second drive
> pulled out, the whole lot then boots and I can use mdadm -a to add the
> second drive to the mirrored pair. The drives resync at a decent speed and
> the pair works fine for the duration, but when I reboot the second drive is
> not part of the mirrored pair unless I manually add it again.
What's the partition type on the second drive?  If you want kernel to 
start software RAID device on boot, all partitions that are component of 
such devices must be tagged as "linux raid autodetect" (type fd).  You
can use fdisk to easily check (use "p" command) and set (use
"t"
command) this.

-- 
Aleksandar Milivojevic <amilivojevic at pbl.ca>    Pollard Banknote
Limited
Systems Administrator                           1499 Buffalo Place
Tel: (204) 474-2323 ext 276                     Winnipeg, MB  R3T 1L7

From: Aleksandar Milivojevic <amilivojevic at
pbl.ca>
> MegaRAID drivers (and hardware they drive) doesn't have very bright 
> history.  When it works, it works.  When it doesn't work, you are
simply
> out of luck.  From what you wrote, seems you belong in "out of
luck"
> category.
> BTW, shouldn't MegaRAID cards be hardware RAID?
Many are, but not all.
The ones that do have an Intel IOP 8030# (i960-based) or
8032#/8033# (StrongARM/XScale-based).
> If you configure RAID in card's BIOS, instead of using software RAID,
> does it than work correctly?
The BIOS is _only_ for 16-bit Int13h (interupt 13 hexadecimal) services.
I.e., boot-time and DOS (including DOS7 aka Win9x/Me in "compatibiltiy
mode").

The presence of a BIOS does _not_ mean it's "hardware" RAID.
In fact, that's how 98% of the "FRAID" cards work -- totally
_useless_ once
a 32/64-bit kernel boots.


-- 
Aleksandar Milivojevic <amilivojevic at pbl.ca>    Pollard Banknote
Limited
Systems Administrator                           1499 Buffalo Place
Tel: (204) 474-2323 ext 276                     Winnipeg, MB  R3T 1L7
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--
Bryan J. Smith   mailto:b.j.smith at ieee.org