Raid 5 steup problems w Ubuntu Server 8.10

Posted on 2008-11-17
Last Modified: 2013-12-15
I am experiencing great problems setting up a Liunx Software Raid 5 system.

My motherboard is a ASRock K10N78-1394 which has 6 SATA connectors. I have set them to work in AHCI mode.
My disks are Seagate's 1.5 TB. I want them to be used as five active and one spare.
My boot medium is a 4 GB USB memory...
The installation CD/DVD drive is also connected via USB, if that's relevant.

First of all, I have read the post on Tom's that issues a warning about my disks:,6558.html and I haven't seen any kernel error like that one yet.

Now, the only time I can access the disks without any comments about "device busy" or "missing super block" or similar, is from the rescue mode shell prompt from the installation CD. Here I have built the entire array three times (each time for about 10 hours). Even if I boot up in single user mode, the drives are "busy".

I use mdadm 2.6.7, and I have zero'd the super blocks before creating the array. Last time, I installed ReiserFS, and one of the disks failed (might have been a freeze, acually) which caused a rebuild. Afterwards, I could mount the array but only in this rescue mode.

Now, as other people are waiting for this server to be up and running, I really need help with this one fast. If you know what's wrong, or what components must be replaced, please tell me. Would it help to get a new SATAII controller?

The disks each have one single (huge) partition. Is there an upper limit for what these tools can handle? Anyway, next time I try (if there will be one) I will shrink these partitions. Their type is set to FD.

Any mdadm command I have tried from the regular prompt has resulted in an error - most often "Device or resource busy", but also "invalid super block" and "Input/output error".

Commands issued:

fdisk - basic stuff
Disk /dev/sdb: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x9146d6b7

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      182401  1465136001   fd  Linux raid autodetect

mdadm --zero-superblock /dev/sd{a,b,c,d,e,f}1
mdadm -Cv /dev/md0 -l5 -n5 -x1 -c128 /dev/sd{a,b,c,d,e,f}1
mkreiserfs /dev/md0
- These last ones work fine in rescue mode and I can follow the process in /proc/mdstat.

After reboot:

$ sudo mount -t reiserfs /dev/md0 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/md0,
       missing codepage or helper program, or other error
       (could this be the IDE device where you in fact use
       ide-scsi so that sr0 or sda or so is needed?)
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

/proc/mdstat reports my failed disk (sda) as spare (S).

$ sudo fsck.reiserfs /dev/md0 --rebuild-sb
reiserfsck 3.6.19 (2003

Will check superblock and rebuild it if needed
Will put log info to 'stdout'

Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes
bread: Cannot read the block (2): (Invalid argument).
reiserfs_open: bread failed reading block 2
bread: Cannot read the block (16): (Invalid argument).
reiserfs_open: bread failed reading block 16

reiserfs_open: the reiserfs superblock cannot be found on /dev/md0.

I am attaching /var/log/messages and dmesg output. Anything else needed?
Question by:obg
    LVL 43

    Expert Comment

    It looks like You have the raid5 configured in the bios - unconfigure.
    Or try using the automatically created device /dev/mapper/something - but I would go with unconfiguring the bios raid array.
    LVL 2

    Author Comment

    It certainly does look like that, doesn't it? However, there are three modes that I can set for my drives in the BIOS. Those are: IDE, AHCI and Raid. They are set to AHCI... I did experiment a little with the built in Raid before I installed a distro that had all required drivers. There might be something that's still messing with with my disks. Maybe I should try HW resetting my BIOS. Do you think that'd help? If there has been some flags set in the MBR or something, then maybe it catches up again as soon as I connect them again...?
    LVL 43

    Accepted Solution

    > There might be something that's still messing with with my disks.
    Of course - the info is saved on hdds. Try switching to raid mode and breaking the configured raid.
    LVL 2

    Author Comment

    Wow! It really seems you're right (again)! - Then, please explain to me why it wasn't messing with my disks during the live CD session - Even though it was during single user mode. This seems very wierd to me...

    Well, I'll wait just a little bit with the final confirmation, just to be sure.
    LVL 43

    Expert Comment

    > please explain to me why it wasn't messing with my disks during the live CD session
    it simply haven't scan hdds for bios-raid signatures - that's all.
    LVL 2

    Author Comment

    Ok, that much I could figure out myself. What I meant was: What is the difference? In one case (live CD) I start from a USB connected DVD drive. In the other I start from a USB connected memory stick. Maybe I'm stuck in 15-20 years old PC science but in my days it was rather straight forward: when the system starts to boot up, then the BIOS is done. So, in case 1 there is no bios raid scan but in case 2 there is...

    Sorry, I just have to understand this, but please don't get me wrong. I am still very grateful for your help.
    LVL 2

    Author Closing Comment

    It seems I'll have to live without knowing all the details around this issue. Thank you very much anyway!

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