RE: Recovering RAID set after OS disk failed

["Kővári Péter" <peter@kovari.priv.hu>]

Hi Davide,

Open / ssh a console on your NAS box, and issue the following command and send us the results: 
$ cat /proc/mdstat

Please also issue the following commands

mdadm --examine /dev/sdX[Y]

Where X is one of the raid drive's name and Y is the partition number, if you created the raid set on partitions. (If not, then leave the number.) So, for example (assuming that your OS drive is /dev/sda, so your raid drives are /dev/sdb, /dev/sdc and so on) issue the following commands:

$ mdadm --examine /dev/sdb
or
$ mdadm --examine /dev/sdb1

and so on for all 4 drives. And send back the results.

p.s.
Before everything else,  you might try  auto assembling th eset by:
$ mdadm -v --assemble --scan

It might assemble your raid set for you successfully out of the box.  (If not, send here the output.)
If this assembles your set successfully, then you just need to save your config in /etc/mdam/mdadm.conf, do an initramfs update and you are good to go.
So to save the config issue:
$ mdadm --examine --scan >> /etc/mdadm/mdadm.conf

then update initramfs so th eset will auto assmble on next boot:
$ update-initramfs -k all -u

Best regards,
Peter
---------------------------------------------------------------------------------------------------------------
: peter@kovari.priv.hu
: pkovari@gmail.com
:  www.kovari.priv.hu

-----Original Message-----
From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Davide Guarisco
Sent: Monday, June 2, 2014 7:38 AM
To: linux-raid@vger.kernel.org
Subject: Recovering RAID set after OS disk failed

Hello and sorry if this is not the place for a relatively “newbie” question.

Five years ago I built a NAS box running on Ubuntu server then-current version. The NAS has 4 SATA drives (the RAID set) and a PATA system drive (for the OS). Now the system drive has failed (click of death). I believe the that RAID data is still safe and sound, but my question is how to proceed in such a scenario. (I do have a backup but it’s fairly old). I do not remember exactly how I created the RAID set, other than being with mdadm and probably RAID 5. 

I have now replaced the failed PATA drive with a new 32 GB PATA SSD, and installed Ubuntu Server 14.04. The system is up and running and it sees the four SATA drives. I have installed Webmin and I am ready to recover the RAID set. 


I read the Wiki and it suggests running a “permutation” Perl script. Is this a reasonable thing to do? 
I could not find much information on a case like this in a Goole search, so any help appreciated. 




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