Comments on: Quick and dirty linux software RAID5

By: Delicious Bookmarks for January 30th through February 1st « Lâmôlabs

Delicious Bookmarks for January 30th through February 1st « Lâmôlabs — Mon, 01 Feb 2010 19:08:17 +0000

[...] Quick and dirty linux software RAID5 | How in the TECH – January 30th ( tags: raid linux howto server raid5 mdadm ) [...]

By: Mad

Mad — Fri, 28 Aug 2009 14:05:02 +0000

This might be the same problem Bando Bando experienced above.
I’ve just installed 4 x 1TB in raid5 in Ubuntu 9.04. After reboot – no md0??? I tried mdadm –assemble –scan, and got only 3 disks. Ok, fine, I’ll add the forth then, I thought. I got device or resource busy. Ok, reboot again, then I only have 2 disks, and array can not be assembled of course. I tried a lot of things like clearing the superblocks, re-partioning etc, same problem still, loses one disk each reboot.
In /etc/mdadm/mdadm.conf it says
DEVICE partitions
CREATE owner=root group=disk mode=0660 auto=yes
HOMEHOST
I replaced these lines with
DEVICE /dev/sd??
ARRAY /dev/md0 UUID=1b0816d7:c82651a0:67e26e6e:a4449dba
The UUID is of course mine, you will find yours using mdadm –detail.
Now it works, I don’t know why. Maybe that I on one disk have a small partition with Ubuntu, and on another disk a swap partition, each 10GB, only then this problem occurs? For example I have another computer where I have 8 dedicated disks in raid5, ie Ubuntu installed on a ninth disk, no changes done in mdadm.conf and despite that everything works fine. Hope this can be of help.

By: Brian

Brian — Thu, 21 May 2009 15:40:44 +0000

AWESOME! Simple, quick and dirty HOW-TO. Thanks so much.

By: Adam Myers

Adam Myers — Sun, 06 Jul 2008 00:05:39 +0000

@Paradexes

Thanks, yeah I’ve noticed that but for some reason my wordpress theme gunks out the double dash.

Glad it proved useful nonetheless!

Edit: I fixed the double dash problem in Wordpress

By: Paradexes

Paradexes — Sat, 05 Jul 2008 23:37:17 +0000

Great howto easiest one I have found. Hopefully someone can take this and GUIfy it for new users.

FYI small typos need fixing

–create*
–raid*
–level*
–chunk*

One dash wont work. Still kick ass article otherwise. Works great in Ubuntu 8.04 and 7.10.

By: Adam Myers

Adam Myers — Wed, 07 May 2008 18:55:26 +0000

Hi Bando,

That step doesn’t appear to be necessary in Ubuntu – I don’t recall doing anything other than the above. I’ll be doing another raid5 setup in the next week or so with Hardy Heron. I’ll update my findings then.

Anyways, thanks for the comment!

By: Bando Bando

Bando Bando — Wed, 07 May 2008 18:12:04 +0000

Guide worked great except my system wouldn’t startup on reboot. I had to use a Recovery Disk to edit out the line in /etc/fstab just so it would boot. It seems there’s one step missing, at least it was required for Fedora 8 x86_64. Anyways. Before rebooting you’ll probably want to:
mdadm –detail –scan –verbose > /etc/mdadm.conf
if you want your system to startup. Like I said could just be a Fedora thing, but I’m betting otherwise. I found this here:
http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch26_:_Linux_Software_RAID
I also used fdisk instead of cfdisk.

By: Adam

Adam — Thu, 27 Mar 2008 03:20:31 +0000

Thanks Ivan! I should have probably included something like this.

By: Ivan Lawrence

Ivan Lawrence — Thu, 27 Mar 2008 01:25:12 +0000

Found it! http://linux-raid.osdl.org/index.php/Detecting%2C_querying_and_testing#Monitoring_RAID_arrays

By: Ivan Lawrence

Ivan Lawrence — Thu, 27 Mar 2008 00:37:24 +0000

Does anyone know how to set up the server to email (or alert another way) for disk failures or array degradation? I have read a few other tutorials but none of them cover proactive disk monitoring.
Thanks,
-Ivan