Replacing failed drive using mdadm

RCO

12/13/23, 11:42 AM

I have a test server running Ubuntu Server 22.04.

The server boots from a small SSD. When setting it up I used mdadm to create a RAID1 with two 1 TB drives for data. After a few months, one of the drives failed. The mirror works. I was able to continue using the server while waiting for a new repalcement drive to arrive.

I followed some instructions in a video I found online and was able to replace the drive and rebuild the array.

One thing bothers me when viewing things using lsblk:

sdc 8:32 0 111.8G 0 disk
├─sdc1 8:33 0 1M 0 part
└─sdc2 8:34 0 111.8G 0 part /

sdd 8:48 0 931.5G 0 disk
├─sdd1 8:49 0 931.5G 0 part
└─md0 9:0 0 931.4G 0 raid1 /mnt/md0

sde 8:64 0 931.5G 0 disk
└─md0 9:0 0 931.4G 0 raid1 /mnt/md0

The original, still-working RAID member is sde. The new replacement is sdd. I followed the instructions in the replacement video in creating the partition sdd1. No such partition is showing for sde.

Running mdadm --detail /dev/md0 shows no errors:

/dev/md0:

         State : clean

Active Devices : 2

Number   Major   Minor   RaidDevice State
   2       8       48        0      active sync   /dev/sdd
   1       8       64        1      active sync   /dev/sde

Did I miss a step creating the original RAID1 array? Should I take some corrective measures or leave well enough alone?

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