mdadm creates /dev/md_d0 and /dev md_d0p1-p4

**spectre_25gt** · May 24th, 2009

I recently set up a software raid1 array and instead of seeing /dev/md0 as I expected, I saw /dev/md_d0 and /dev/md_d0p1-p4 show up. Had I only seen md_d0, I would guess that the addressing had just changed since the last time I set up software raid (ubuntu 6.06). The other entries leave me wondering, though.

Could anyone shed some light on this apparent change? I haven't seen any information on it no matter how hard I look.

**fjgaude** · May 25th, 2009

Do you recall what command you used to create the array?

**grantemsley** · May 25th, 2009

Could anyone shed some light on this apparent change? I haven't seen any information on it no matter how hard I look.

That looks like the format for a partitionable raid array. If you created it with -a or --auto options, you might get that.

I'm not sure what the pros or cons are of setting up the array that way.

**spectre_25gt** · May 27th, 2009

I can't believe my history goes back this far. It should have been:

Code:

sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1

It looks like I tried it a couple of times in different ways, though... I had gotten some errors saying that /dev/sdb1 or /dev/sdc1 were busy and couldn't be opened. I'm guessing the raid had already started syncing and I wasn't aware.

At any rate, those were the only switches I used. That I know for sure.

**fjgaude** · May 27th, 2009

Were the drives, partitions ever used in a raid array before? If so, were the superblocks zeroed before you used the --create command?

Can you simply start over?

**spectre_25gt** · May 28th, 2009

I zeroed the superblock a couple of times, but it just kept coming out that way.

I was able to use /dev/md_d0 as the raid device. I'm really more interested in finding out what's behind this than coming up with a resolution. There's obviously something going on that could be really useful to know about.

Thanks for all of the input so far, btw.