RAID 5 system degraded already

Only installed OMV last night on a HP N40L microserver. I have a 250GB disk on which I installed OMV and 3x500GB disks that I built a RAID5 array with. The disks weren't new, but as far as I was aware, they were good.

The build process seemed to go quite smoothly and took a few hours to complete.

Last night I used the USB Backup plugin to copy the contents of an external USB drive to a share - about 400GB of data.

I am just trying to get my head around moving data around effectively, and I have noticed that my RAID 5 array is now degraded. Only 3 disks in total are visible in the Physical Disks view - my 250GB OS drive and 2 of the 3 array drives. Where is the third? If it had failed, I would at least expect it to show up in here somewhere...

Please bear with me as I am very new to all of this.

In the console I typed in
fdisk -l
and clicked return. I am faced with all sorts of figures, so I am not sure what info to give you. A couple of things that stand out are as follows:-

Disk /dev/sdc doesn't contain a valid partition table
Disk /dev/sdd doesn't contain a valid partition table
Disk /dev/md127 doesn't contain a valid partition table

There is also other information that has scrolled off my screen.

Is this any use?

When I type
cat /proc/mdstat
md0 : inactive sdd [2] (S)
488385560 blocks super 1.2

md127 : active raid5 sdb[0] sdc [1]
unused devices: <none>

When I logged into the web console, I noticed that it was sdd that was missing. I think sda is the OS drive, and my raid was built of sdb, sdc and sdd.

When I look at my N40L server, there are 4 drive slots. The left most drive is the 250GB OS drive (sda). I therefore assumed that the second slot must be sdb, the third slot sdc and the last slot sdd.

Not wanting to hang around, I pulled out the fourth drive and replaced it with the only other drive I had lying around, which is a 1TB drive. Rebooting and messing around with the web admin, I seem to have managed to tell the system to rebuild the array using the new drive.

Its been in there about 20 minutes now and is still showing that the rebuild is at 0%. I hope this works. Not the greatest of starts in my world of OMV.

No sorry, didn't see the commands you suggested before I had pulled the disk out.

Thanks for your words of encouragement - much appreciated.

I am a little worried that the sytem has allegedly been rebuilding for over 45 minutes and it is still at 0%. Do you think I have an issue here?

having typed
cat /proc/mdstat it seems it has completed 0.4% and speed is 393k/sec!!!!

Rebooted and chose the 'safe' mode. Now reading 1500k/sec. At that speed it thinks it will take nearly 4 days to rebuild. Does that seem about right to you?

Checking again and it is now at 201k/sec

What could be causing things to be so slow?

Just typed tail /var/log/messages and nothing is jumping out as an error. A few references to usb 5-1, but that might just be a reading of available usb ports I guess?

When my machine reboots, I do see a few red ERROR/FAILED messages pop up but it is so quick I don't get a chance to see what they are.

Rebooted in normal mode and it seems to be running at about 1400k/sec. Still really slow so I am questioning the advantages of RAID in my situation. With hardware RAID, I imagine you get much more speed, but this is software raid.

Am I flogging a dead horse? Should I just reinstall the N40L with a license of Windows Home Server 2011 and use a combination of regular external backups and online, offsite backups (aka Crashplan)?

I think I will do as you suggest and forget aboput raid. How do I delete the raid array I have created? The 'delete' button is greyed out.

Many thanks - will give that a try this evening

Managed to delete the array and rebuilt 3 separate drives with different shares on each.
500GB for Photos
500GB for music
1TB for backup (for when I learn how to use rsync)

Is there a way to test the integrity of my hard disks within OMV? I know there is the SMART monitoring, but I am not really sure what to do with that or indeed if it is the right thing to be using.