[BlueOnyx:17634] Re: Raid1 issue

[Chris Gebhardt - VIRTBIZ Internet]

On 5/20/2015 11:13 AM, Tom wrote:
> It appears one of my new hard drives is defective and failing. I replaced
> the drive with a new one. An hour or so has gone by and I received an email
> that RAID has failed. So I ran cat /proc/mdstat and received the following:
>
> [root at ns ~]# cat /proc/mdstat
> Personalities : [raid1]
> md0 : active raid1 sda1[1]
>        819136 blocks super 1.0 [2/1] [_U]
>
> md126 : active (auto-read-only) raid1 sdb2[0]
>        243625852 blocks super 1.1 [2/1] [U_]
>        bitmap: 2/2 pages [8KB], 65536KB chunk
>
> md127 : active (auto-read-only) raid1 sdb1[0]
>        511988 blocks super 1.0 [2/1] [U_]
>
> md1 : active raid1 sda2[1]
>        243188736 blocks super 1.1 [2/1] [_U]
>        bitmap: 2/2 pages [8KB], 65536KB chunk
>
> Do I need to recreate the RAID1 or wait for it to rebuild on its own?

What is the "md126" and "md127" from?  It looks like you added a disk 
into /dev/sdb that had pre-existing RAID data on it.  That's going to be 
a problem, and you'll need to unmount anything that has been mounted 
from /dev/sdb and then fdisk and repartition.   Then you can add the new 
disk into the RAID, but you'll need to walk it through manually.

Here's a how-to that can help you:
https://www.howtoforge.com/replacing_hard_disks_in_a_raid1_array

Be very careful, of course, when you're working with partitions.  The 
old woodworking adage "measure twice, cut once" should apply here!

-- 
Chris Gebhardt
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