[NBLUG/talk] More hard drive problems

[Lincoln Peters]

On Oct 2, 2005, at 9:02 PM, Lincoln Peters wrote:

>
> On Oct 2, 2005, at 8:17 PM, Lincoln Peters wrote:
>
>> When the surface scans finish, I'll review the man pages for  
>> reiserfsck and mdadm one more time, and if I don't see any obvious  
>> thing to try that I haven't already tried, I'll try the Knoppix CD.
>>
>
> OK, the surface scans finished on all three hard disks.  Just the  
> one I mentioned has bad blocks.  Therefore, the RAID-5 array  
> *should* be usable, but when I type in:
>
> # mdadm --run /dev/md1
>
> I get the following output (copied by hand; might have typos):
>
> raid5: device hda3 operational as raid disk 0
> raid5: device hdg1 operational as raid disk 2
> raid5: cannot start dirty degraded array for md1
> RAID5 conf printout:
>  --- rd:3 wd:2 fd:1
>  disk 0, o:1, dev:hda3
>  disk 2, o:1, dev:hdg1
> raid5: failed to run raid set md1
> md: peers->run() failed ...
> mdadm: failed to run array /dev/md1: invalid argument
>
>
> (The damaged disk that would normally appear as raid disk 1 is hde3)
>
> This leads me to doubt that there are any superblock errors on the  
> filesystem as I had initially expected (the superblock error was  
> most likely generated because the array was inactive).  It looks  
> like purely a RAID issue.
>
> I suppose that it would make sense if mdadm was reluctant to start  
> a RAID-5 array that was missing one device (since if a second  
> device failed, there would be actual data loss), but I thought if I  
> wanted to I *could* continue running even if a disk failed!  It's  
> not *that* hard to imagine a situation where one might need to  
> start an array that's degraded but still functional (I'm in such a  
> situation right now!).

Never mind; I just discovered that I should have done a Google search  
for "mdadm start degraded array" (minus the quotation marks), and I  
would have found the answer very quickly.

 From http://www.issociate.de/board/index.php? 
t=msg&goto=475068&rid=0#msg_475068

I had the exact issue on the weekend this is how I fixed it:
mdadm -S /dev/md0
mdadm -Af /dev/md0 /dev/hdm4 /dev/hde2 /dev/hdo2 /dev/hdh2 /dev/hdf2
/dev/hdg2


I changed the device names to fit my configuration:
# mdadm -S /dev/md1
# mdadm -Af /dev/md1 /dev/hda3 /dev/hdg1

And now the array, while still degraded, is up an running.  And the  
superblock of my /home directory is in perfect condition.  I'm  
currently running fsck on the array, though, just to be safe before I  
try to use it.

Needless to say, I'm going to use the computer as little as possible  
until I can replace the hard disk.  Fortunately, I think that the  
disk is still under warranty.


Lincoln Peters
lmpeters at mac.com