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Old 04-07-2011, 02:36 AM   #1
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MDADM error: Help creating a RAID 1 RAM disk

I am trying to create a Raid 1 ram disk. Below are the commands I used:
[root@abidbodal dev]# mke2fs -m 0 /dev/ram8
[root@abidbodal dev]# mount /dev/ram8 /mnt/rd8
[root@abidbodal dev]# mke2fs -m 0 /dev/ram9
[root@abidbodal dev]# mount /dev/ram9 /mnt/rd9
[root@abidbodal abidbodal]# mount /dev/ram8 /mnt/rd8
[root@abidbodal abidbodal]# mount /dev/ram9 /mnt/rd9

[root@abidbodal md0]# mdadm --create /dev/md0 --chunk=4 --level=1 --raid-devices=2 /dev/ram8 /dev/ram9
mdadm: device /dev/ram8 not suitable for any style of array

Above is the error I got. I don't understand what the error is saying. I tried Googling it, but that didn't help much. Oh, and I'm running Fedora 12.

Oh, I did check if the RAM was mounted, and it was.
[root@abidbodal md0]# mount | grep ram*
/dev/ram1 on /mnt/rd1 type ext2 (rw)
/dev/ram2 on /mnt/rd2 type ext2 (rw)
/dev/ram3 on /mnt/rd3 type ext2 (rw)
/dev/ram4 on /mnt/rd4 type ext2 (rw)
/dev/ram5 on /mnt/rd5 type ext2 (rw)
/dev/ram6 on /mnt/rd6 type ext2 (rw)
/dev/ram7 on /mnt/rd7 type ext2 (rw)
/dev/ram8 on /mnt/rd8 type ext2 (rw)
/dev/ram9 on /mnt/rd9 type ext2 (rw)
/dev/ram10 on /mnt/rd10 type ext2 (rw)
/dev/ram11 on /mnt/rd11 type ext2 (rw)
/dev/ram12 on /mnt/rd12 type ext2 (rw)

Old 04-07-2011, 04:35 AM   #2
Registered: Jun 2009
Location: Penang, Malaysia
Distribution: Mageia, CentOS, Ubuntu
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Well. I've never tried using ramdisks to make an array before. I'm not even sure if that is possible. But I did notice that you mounted the ramdisks before running mdadm. You should not mount the devices that are going to be members of an array.

You need to first create the array by running 'mdadm --create /dev/md0 .....'
Then format the array device, as in 'mke2fs -j /dev/md0'
Finally, mount the formated array device. 'mount /dev/md0 /mnt/raid'
Old 04-07-2011, 10:08 AM   #3
Registered: Jun 2005
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Distribution: Ubuntu10.04
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Maybe this link is of any help ...
Old 04-10-2011, 01:33 PM   #4
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Registered: Apr 2011
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Ongte's answer solved my problem. Thanks


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