Topic: RAID degradation

[milsey]

I have two HDs connected as masters (primary and secondary) and SME server installed using software RAID1.  It has been working fine until recently when a series of power fluctuations killed the MB. Took it to the shop to replace the MB and they connected the HDs as primary and secondary.  Now, if I run exec lsraid -a /dev/md0 I get
[dev 9, 0]  /dev/md0   abcd.abcd.abcd.etc online
[dev ?, ?]  (unknoww)  0000.0000.0000.etc missing
[dev 22, 1] /dev/hdc1  abcd.abcd.abcd.etc good

Output for devices md1 and md2 are identical except line 3 is [dev 22, 2 or 3) and hdc2 or hdc3.  

I have notices at shutdown and boot messages the something is amiss.  

My concern is line 2 with the 'unkown' and 'missing'
Does this mean I have only one HD working and how do I remedy the fault without a reinstall and interuption to business?

[ldkeen]

Milsey,
What is the outout of cat /proc/mdstat?

[milsey]

Milsey,
What is the outout of cat /proc/mdstat?

ldkeen
Thanks for your input.  
Output is:
Personalities : [raid1]
read_ahead 1024 sectors
md2 : active raid1 hdc3[1]
      264960 blocks [2/1] [_U]

md1 : active raid1 hdc2[1]
      38708544 blocks [2/1] [_U]

md0 : active raid1 hdc1[1]
      104320 blocks [2/1] [_U]

unused devices: <none>

It appears that one of the disks is out of action

I am bit of a novice and thought that the system would detect and repair etc but obviously not.  At least my suspicions are confirmed.  

Next step?

Thanks again

[ldkeen]

Hi Milsey,
It looks like your primary master drive (/dev/hda) has packed it in. You could try rebuilding the raid with
#/sbin/raidhotadd /dev/md0 /dev/hda1
#/sbin/raidhotadd /dev/md1 /dev/hda2
(/dev/md2 is your swapfile). If the drive is in fact stuffed then this wont work and you'll have to grab another
drive the same size as your good drive and follow one of the howto's regarding replacing a failed drive. Here's a link to one of the howto's:
http://no.longer.valid/phpwiki/index.php/Migrating%20a%20Raid%201%20to%20bigger%20harddisks%20with%20Knoppix
Regards Lloyd

[milsey]

Idkeen

Thanks for the tip.  I will look into it.  Back up 1st.  

Will keep you posted. Thanks again.

[milsey]

I found the following link helpful.

http://aplawrence.com/Linux/rebuildraid.html

I performed a fdisk 'p' of both the active and inactive devices and they were identical.  

I am in the midst of a rebuild - "raidhotadd" but 9 hours to wait for the results.  I'll publish results on 18 Apr as I don't think I'll wait around.  

Regards

Max


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[milsey]

RAID back up on two drives.  Problem fixed.  Using radihotadd did the trick.  

Thanks for the info Lloyd.  


Regards

Max

[ldkeen]

Milsey,
Don't crack open the VB's yet (or whatever it is you westerners drink over there ). If the drive is in fact stuffed then it may still drop out of the array. Keep a close eye on it over the next couple of days or better still install the raidmonitor package (sorry don't have a link to that addon).
Regards Lloyd

[milsey]

Hi Lloyd,

As far as I can make out the suspect drive is ok.  I plugged the drive in by itself and it booted up ok and the old data was still there.  So, I think I am pretty safe in cracking a cold one.  

Thanks again.  

Max