[SOLVED] Software RAID and fdisk issue

koiril · 06-16-2009, 09:21 AM

I've been been trying with no avail to setup a RAID 5 array using mdadm. I'm semi new to the whole linux scene by the way. Here's how the story goes:

I downloaded Ubuntu Server edition and installed it on my PC with no problems but before doing that I first setup my ASUS P5Q Pro motherboard's raid in RAID 5. Once everything was installed I booted up Linux and ran the usual upgrades/updates. Once all that was done I installed mdadm; fdisk'ed 3 1TB drives (sda,sdb,sdc) to each have 1 partition of type 'fd'; then used the following command to create my array:

Code:

sudo mdadm -Cvf /dev/md0 -l5 -n3 -c64 /dev/sd{a,b,c}1

Beautiful! Everything worked perfectly.

So, now that I have the array up and running I make sure to edit /etc/mdadm/mdadm.conf so that it knows I have an array using this:

Code:

sudo mdadm --detail --scan --verbose > /etc/mdadm/mdadm.conf

That works fine as well.

Next I run mkfs.ntfs on /dev/md0 and put a new entry in 'fstab':

Code:

 /dev/md0      /storage     ntfs    defaults    0 0

After that I run 'mount -a' to mount it.

Now everything is mounted and working wonderfully but just to be sure I decided to reboot (and I'm glad I did). When the PC comes back online the drive is no longer mounted. Not only that /proc/mdstat has nothing in it. As well as /proc/partitions says I don't have any partitions on the drives I fdisk'ed yet fdisk -l says I do. Now I'll try to give you as much information as possible to hopefully solve my problem of my array not auto loading on boot.

Code:

     koiril@Sloth:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 9.04
Release:        9.04
Codename:       jaunty
koiril@Sloth:~$

Code:

     koiril@Sloth:~$ sudo mdadm -A /dev/md0 /dev/sd{a,b,c}1
mdadm: cannot open device /dev/sda1: No such file or directory
mdadm: /dev/sda1 has no superblock - assembly aborted
koiril@Sloth:~$

Code:

     koiril@Sloth:~$ cat /proc/partitions
major minor  #blocks  name

   8        0  976762584 sda
   8       16  976762584 sdb
   8       32  976762584 sdc
   8       48  312571224 sdd
   8       49  306608526 sdd1
   8       50          1 sdd2
   8       53    5960083 sdd5
koiril@Sloth:~$

Code:

  koiril@Sloth:~$ sudo fdisk -l
[sudo] password for koiril:

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xb308ff24

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1      121601   976760001   fd  Linux raid autodetect

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x087acc0e

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      121601   976760001   fd  Linux raid autodetect

Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xc7b9a7a7

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1      121601   976760001   fd  Linux raid autodetect

Disk /dev/sdd: 320.0 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x33e133e1

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1               1       38171   306608526   83  Linux
/dev/sdd2           38172       38913     5960115    5  Extended
/dev/sdd5           38172       38913     5960083+  82  Linux swap / Solaris
koiril@Sloth:~$

Code:

    koiril@Sloth:~$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
unused devices: <none>
koiril@Sloth:~$

mostlyharmless · 06-16-2009, 10:59 AM

Quote:

but before doing that I first setup my ASUS P5Q Pro motherboard's raid in RAID 5.

Could you be more specific? If you were using mdadm, then you don't want to use the motherboard RAID. If you were using the firmware RAID then you probably wanted to use dmraid.

koiril · 06-16-2009, 11:13 AM

Oh ok. I was under the impression that to have software RAID of any form you also had to have the RAID on your Motherboard setup. I was using the Intel ICH10R Southbridge chip with Intel Matrix Storage Manager ROM utility. I'll try disabling the Motherboard RAID and setup mdadm that way.

Which do you think would be easier to recover from if there is a drive failure? Motherboard RAID with dmraid or pure software RAID using mdadm?

Thanks, for the response by the way.

Dudydoo · 06-16-2009, 12:59 PM

You don't want to run RAID 5 on the motherboard, which is effectively fake RAID - performance will be dire. Unless you are using real hardware raid (think big bucks), i'd recommend just use mdadm.

And it is very easy with mdadm to replace a faulty drive.

mostlyharmless · 06-16-2009, 01:14 PM

Firmware RAID is essentially software RAID, so really there shouldn't be a performance hit between it and mdadm. There's been plenty written on the pros and cons of firmware vs mdadm; probably the only good reason to use the firmware RAID is for dual booting in RAID with Windows.