Take the 2-minute tour ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

Array info:

/dev/md0 -> /dev/sda1 and /dev/sdb1

/dev/md2 -> /dev/sda2 and /dev/sdb2

Partition info:

/boot -> /dev/md0

/ -> /dev/md1

I have two drives that are setup as RAID1 using software RAID on Redhat. I added two additional drives (same size) and I would like to conver the RAID1 to a RAID10. The problem I'm having is adding the last drive to the array. I've gotten as far as creating a RAID10 with two missing devices but as soon as I add the last drive, all hell breaks loose. It seems /dev/sda1 is the culprit.

What I'm not too sure about is how to create the RAID10. I've tried the following

mdadm --create /dev/md2 --level=raid10 --raid-device=4 /dev/sdc1 missing /dev/sdd1 missing

I then proceeded to fail /dev/sdb1 from /dev/md0 and added that partition to /dev/md2. I proceeded to install the MBR on EACH partition since boot resides on /dev/sdx1 on each drive. As a test, all is well, I'm able to boot back into the system once I do a quick reboot. Now, when I go add the last drive /dev/sda1, it breaks. I attempted to install grub on /dev/sda1 and I get the following ...

grub> root (hd0,0) /dev/sda
root (hd0,0) /dev/sda
Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd0)
setup (hd0)
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... no

Error 2: Bad file or directory type

At this point, the array is hosed I believe. I rebooted the server and it refuses to boot.

share|improve this question

1 Answer 1

You can't RAID-0 or RAID-10 the /boot partition. Under both RAID schemes the data is interleaved across two or more disks -- and when the computer goes to read it, it doesn't know how the data is spread across those disks.

It would be like giving you a box of Alphabits and asking you to construct a document in a foreign language describing how to construct a document out of Alphabits.

share|improve this answer
    
Then why would it work w/ 3 drives but it fails once I add the last drive? –  luckytaxi Sep 28 '12 at 19:12

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.