[SOLVED] Raid device /dev/md2 not sustaining

vinaytp · 05-19-2010, 07:17 AM

Dear All,

I am trying to configure RAID 1 on Fedora12 Virtual Machine.

Initially I had two drives /dev/sda and /dev/sdb which are configured with RAID 1.

Now I have attached two more hard drives /dev/sdc and /dev/sdd in which I am trying to configure RAID1. I have followed following steps to mount newly created Raid array on /var

1. Created /dev/sdc1 and /dev/sdd1 as Linuxraid (ID:fd) with 200MB of space

2. Created raid array

Code:

# mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/hdc1 /dev/hdd1

3. Created ext3 filesystem

Code:

# mkfs.ext3 /dev/md2

4. Mount it on a test directory

Code:

# mount /dev/md2 /mnt/var

5. Copy the files of /var to /mnt/var/

Code:

cp -ar /var/. /mnt/var/

6. Unmount the volume

Code:

umount /mnt/md2

7. mount on /var

Code:

mount -t ext3 /dev/md2 /var

Now I could see all the files in side /var and /dev/md2 is properly mounted on /var

Also I added following line to /etc/fstab

Code:

/dev/md2   /var   ext3  defaults 1 2

Even after mount -a I can see the /dev/md2 mounted on /var

But when I reboot the machine system goes to maintainance mode and asks for root password, because created raid arrary /dev/md2 is not sustaining after reboot.

What additional command I have to execute to make /dev/md2 permanent after reboot ?

Thanks in advance.

alli_yas · 05-19-2010, 08:50 AM

Hi Vinaya

Think everything you did is 100% - except i think you missed one step.

I've done this before and I remember that you need an mdadm.conf file that stores your RAID set information for persistence.

Similar to the example below (taken from a good RHCE tutorial I found online)

Code:

 Create the mdadm.conf Configuration File

Your system doesn't automatically remember all the component partitions of your RAID set. This information has to be kept in the mdadm.conf file. The formatting can be tricky, but fortunately the output of the mdadm --detail --scan --verbose command provides you with it. Here we see the output sent to the screen.

[root@bigboy tmp]# mdadm --detail --scan --verbose
ARRAY /dev/md0 level=raid5 num-devices=4 
UUID=77b695c4:32e5dd46:63dd7d16:17696e09
   devices=/dev/hde1,/dev/hdf2,/dev/hdg1
[root@bigboy tmp]#


Here we export the screen output to create the configuration file.

[root@bigboy tmp]# mdadm --detail --scan --verbose > /etc/mdadm.conf

Check out this link where I found the above (it's pretty much doing everything you've done except for the part I've highlighted above):
http://www.linuxhomenetworking.com/w..._Software_RAID

Hope this solves your problem

Cheers
Yas

vinaytp · 05-19-2010, 11:57 AM

Hi Yas,

You are simply awesome. It worked, I added /etc/mdadm.conf file.

Thanks a looot !!!

alli_yas · 05-20-2010, 02:04 AM

No problemo

Mark the thread as SOLVED so that other peeps can use it as well