[SATLUG] First question - RAID5 quit working

Samuel Leon satlug at net153.net
Sun Aug 16 15:24:29 CDT 2009


David Labens wrote:
> First, I apologize that I've been part of the group online since DECEMBER, and this is my first attempt to contact.  Life has been busy, but I'm not making excuses.
> 
> In December, I built a home server with an Asus motherboard & AMD 6400 processor & 4 gb RAM.  It's got an 80 gb HDD that is used exclusively for the OS (Linux Ubuntu 8.10 Server, running mostly headless unless boot-up visual is required, like right now), and 4 250 gb HDDs that are s/w configured as RAID5.
> 
> Everything has worked exceptionally well (built in December, not a glitch until 2 weeks ago), then, suddenly, I started getting errors trying to rename a folder.  I did a shut-down and reboot, and the RAID5 is no longer mounting.
> 
> Here's some current diagnostics:
> 
> root at RCH-SERVER:/boot/grub# cat /proc/mdstat
> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
> md0 : inactive sde1[0](S) sdc1[4](S) sdb1[2](S) sda1[1](S)
>       976783360 blocks super 1.0
> 
> unused devices: <none>
> 
> And, I've tried:
> 
> root at RCH-SERVER:/home/admiral# mdadm --assemble --scan
> 

> 				mdadm: /dev/md/0 assembled from 2 drives - not enough to start the array.
> 			
> 		
> 
> I KNOW that two brand new Western Digital HDDs did not go bad simultaneously, and really doubt that either of them went bad.  I read that it's a known problem that they get busied out by the OS, so I'm trying thinking this is the issue.
> 
> UNFORTUNATELY, I put off buying 1 tb drives for backup, and all our recipes, family pics, real estate, music, etc. is on there.  I have just received and installed one on in my Win XP Pro box, so I'm ready to do a first backup IMMEDIATELY upon getting the RAID5 array back working.
> 
> Any suggestions?  Any thoughts?  We're on a limited budget, but I'd be willing to pay someone who can make it work!
> 
> Thanks,
> 
> David Labens
> 
> San Antonio, TX
> 

Oh yuck. You are on pins and needles! If there is important data on here 
then the first thing that I would do is pray! Then spend the next hour 
(or maybe 2) reading the manual page: http://man-wiki.net/index.php/8:mdadm
You are going to have to force it to assemble.  Pretty much the thing as 
this guy: 
http://www.linuxquestions.org/questions/linux-newbie-8/mdadm-question.-disk-failed-3-out-of-5.-742807/ 
Do not make the mistake like this guy and think that restarting the 
machine is going to magically fix anything.  In fact, I would not 
restart the machine again until the array is fully rebuilt and synced.

So yes, step one, see if forcing will work:
mdadm --assemble --scan -f


Also always make sure that email alerts are set up with mdadm.  To check 
that email alerts are working do mdadm --monitor --scan --test. This 
will send an email to the root account on the server.  And on my server, 
all of root's emails get sent to my main email account so I can keep an 
eye on things...

Sam


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