Replacing a failed drive in a software RAID
Each Elastic Metal server uses a RAID1 configuration after installation from the Scaleway console. If you want to change the RAID configuration of the server, you can modify the RAID array using rescue mode.
You may need certain IAM permissions to carry out some actions described on this page. This means:
It is recommended to make a backup of your data before proceeding.
Boot server in rescue mode from the Scaleway console.
Log in to the server using the rescue account:ssh em-XXX@<your_elastic_metal_ip>Tip:
The rescue credentials are available from your server’s status page in the Scaleway console.
Run the following command to make sure all disk caches are written to the disk:sync
Mark the failed disk as failed using
mdadm:mdadm --manage /dev/md0 --fail /dev/sdb2
Visualize the existing
mdadmRAID devices by running the following command:cat /proc/mdstat
An output as follows displays:Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]md126 : active (auto-read-only) raid1 sdb3 sda3974869504 blocks super 1.2 [2/2] [UU]resync=PENDINGbitmap: 8/8 pages [32KB], 65536KB chunkmd127 : active (auto-read-only) raid1 sdb2(F) sda2523264 blocks super 1.2 [2/2] [UU]unused devices: <none>
The faulty device is marked with
Remove the failed disk using the
mdadm --managecommand:root@elastic-metal:~# # mdadm --manage /dev/md0 --remove /dev/sdb2
Contact the technical support to replace the failed disk with a working one.
Once the failed disk is replaced, copy the partition table of the source disk to the new disk:sfdisk -d /dev/sda | sfdisk /dev/sdbImportant:
sfdiskcommand above replaces the entire partition table on the new disk with the one of the source disk. Modify the command if you require preserving other partition information on the disk.
Create a mirror of the source disk using the
mdadmcommand:mdadm --manage /dev/md0 --add /dev/sdb2
Verify the status of the configuration:mdadm --detail /dev/md0Tip:
Use the following command to show the progress of the recovery of the mirror disk:cat /proc/mdstat