Raid 1 disk failed, cannot make active single spare that was rebuilding

I had a 2 disk raid 1. While one of the disks was syncing, the other failed! The failed disk cannot be used, it is really dead (any attempt to access it blocks for 2 minutes and nothing can be read). I have send it back to the store for replacement as it is in the warranty period.

So I am left with only 1 working disk, but it was marked as spare. I cannot start the raid...

I would like to mark this disk as active (not spare) and start the raid with this single disk to be able to copy all data.

How can I do that?

I have tried to stop the raid and force start with the single disk:

sudo mdadm --stop /dev/md128
mdadm: stopped /dev/md128

sudo mdadm --assemble --force /dev/md128 /dev/sda1
mdadm: /dev/md128 assembled from 0 drives and 1 rebuilding - not enough to start the array.

Here is some info:

cat /proc/mdstat

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md128 : inactive sda1[2](S)
      4883637248 blocks super 1.2

unused devices: <none>


sudo mdadm -D /dev/md128
/dev/md128:
       Version : 1.2
    Raid Level : raid0
 Total Devices : 1
   Persistence : Superblock is persistent

         State : inactive
Working Devices : 1

          Name : clevo2:128
          UUID : 3318ae78:679f7afc:57f6521a:11cd3fef
        Events : 64101

Number   Major   Minor   RaidDevice

   -       8        1        -        /dev/sda1



sudo mdadm --examine /dev/sda
/dev/sda:
   MBR Magic : aa55
Partition[0] :   4294967295 sectors at            1 (type ee)



sudo mdadm --examine /dev/sda1
/dev/sda1:
       Magic : a92b4efc
    Version : 1.2
Feature Map : 0x3
 Array UUID : 3318ae78:679f7afc:57f6521a:11cd3fef
       Name : clevo2:128
Creation Time : Fri Jul 19 20:05:09 2019
 Raid Level : raid1
Raid Devices : 2

Avail Dev Size : 9767274496 (4657.40 GiB 5000.84 GB)
 Array Size : 4883637248 (4657.40 GiB 5000.84 GB)
Data Offset : 264192 sectors
Super Offset : 8 sectors
Recovery Offset : 5598464 sectors
Unused Space : before=264112 sectors, after=0 sectors
      State : clean
Device UUID : 0af4c6d9:269b1e71:5d612699:048a258f

Internal Bitmap : 8 sectors from superblock
Update Time : Wed Feb 12 19:41:12 2020
Bad Block Log : 512 entries available at offset 32 sectors
   Checksum : 8aea8502 - correct
     Events : 64101


Device Role : Active device 1
Array State : AA ('A' == active, '.' == missing, 'R' == replacing)

Did you, perchance, make a backup recently?

Yes, I have a backup that is bout 1 day older than what I had in the raid.

Good. To lose only one day is not so bad.

The normal results if a 2 drive raid-1 drive fails while the other is NOT in sync is that you rebuild your raid with new devices and load from install media and backup. While no raid replaces backups, raid-1 protects against single drive failures at best. You had a two drive situation. It takes Raid-6 to provide reliable two drive protection, and that requires at least four drives.

I have seen people get lucky, but a reload is the more reasonable expectation.

Thanks wpeckham.

Regarding this, you would say it is not possible?

I would like to mark this disk as active (not spare) and start the raid with this single disk to be able to copy all data.

I did not say it is not possible. I am saying that the odds are against success.

Originally Posted by luis.alexandre I would like to mark this disk as active (not spare) and start the raid with this single disk to be able to copy all data.

I think the short answer is that the second disk doesn't contain the data. A spare disk is just that - not a contributor to the array until it it is (fully) synched at some point.

But it was at a given point, part of the array: it was one of the 2 active drives. Somehow it became a spare. And when there was a sync process going on, the other active disk failed.

So, if there is a way to change the disk from spare (rebuilding) to active, I would like to try it even if the odds are not good, because the alternative is getting nothing out of it.